Power transmission equipment, methods and programs used by power transmission equipment

Abstract

This invention provides a technology for appropriately determining the state between power transmission equipment and power receiving equipment. [Solution] A power transmission device according to one aspect of the present disclosure is a power transmission device that wirelessly transmits power to a power receiving device, and is characterized by comprising: a receiving means for receiving first information from the power receiving device; and a determination means for determining a coupling state based on the characteristics of a first reference power transmission device used by the power receiving device to determine the first information, the characteristics of a second reference power transmission device having the same characteristics as the power transmission device, and the first information.

Description

[Technical Field]

[0001] This disclosure relates to power transmission equipment, methods and programs used by power transmission equipment. [Background technology]

[0002] Patent Document 1 discloses a power transmission device that improves the accuracy of detecting metallic foreign objects by detecting the state of electromagnetic coupling with the secondary coil based on a correction value, thereby suppressing the influence of the metal casing of a portable device or the like, which is the receiving side (secondary side). Hereinafter, the state of electromagnetic coupling will also be referred to as the electromagnetic coupling state or simply the coupling state. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2012-244732 [Overview of the project] [Problems that the invention aims to solve]

[0004] The coupling state between the power transmission device and the power reception device is affected by the distance between the power transmission coil and the power reception coil. Therefore, in the conventional technology described above, if the coefficient (correction value) used to detect or determine the coupling state between the power transmission device and the power reception device is not determined based on the distance between the power transmission coil and the power reception coil, it may not be possible to properly determine the coupling state. As a result, it may become impossible to properly detect metallic foreign objects, and wireless power transmission from the power transmission device to the power reception device may not be performed properly.

[0005] One aspect of this disclosure, in view of the above, aims to provide a technology for appropriately determining the state between a power transmission device and a power receiving device. [Means for solving the problem]

[0006] A power transmission device according to one aspect of the present disclosure is a power transmission device that wirelessly transmits power to a power receiving device, and is characterized by comprising: a receiving means for receiving first information from the power receiving device; and a determination means for determining a coupling state based on the characteristics of a first reference power transmission device used by the power receiving device to determine the first information, the characteristics of a second reference power transmission device having the same characteristics as the power transmission device, and the first information. [Effects of the Invention]

[0007] According to one aspect of this disclosure, the state between the power transmission device and the power receiving device can be appropriately determined. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing an example configuration of a wireless charging system according to the first embodiment. [Figure 2] This is a functional block diagram showing an example configuration of a power transmission device according to the first embodiment. [Figure 3] This is a functional block diagram showing an example configuration of a power receiving device according to the first embodiment. [Figure 4] This diagram illustrates the threshold setting method for state detection using the Power Loss method. [Figure 5] This is a diagram explaining the Q-value measurement method. [Figure 6] This is a block diagram showing an example of the functional configuration of the control unit of a power transmission device according to the first embodiment. [Figure 7] This flowchart shows an example of processing in a power transmission device. [Figure 8] This is a flowchart showing an example of processing by a power receiving device. [Figure 9] This diagram illustrates the distance between the antenna (coil) and the enclosure. [Figure 10] This flowchart shows an example of processing by a power transmission device according to the first embodiment. [Figure 11] This is a flowchart showing an example of processing by a power receiving device according to the first embodiment. [Figure 12]This figure illustrates the model and coordinate system according to the third embodiment. [Figure 13] This is a flowchart showing an example of processing by a power transmission device according to the third embodiment. [Figure 14] This is a flowchart showing an example of processing by a power transmission device according to the third embodiment. [Figure 15] This is a flowchart showing an example of processing by a power receiving device according to the third embodiment. [Figure 16] This figure illustrates a model according to the third embodiment, where the angle between the interface surface of the power transmission device and the interface surface of the power receiving device is not zero. [Modes for carrying out the invention]

[0009] The embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. Although the embodiments describe several features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the accompanying drawings, the same or similar configurations are given the same reference numeral. Each embodiment shows a wireless charging system to which a wireless power transmission system is applied. As an example, wireless power transmission based on the standards formulated by the Wireless Power Consortium (WPC), a standardization organization for wireless charging (hereinafter referred to as the WPC standard), will be described. An example of a WPC standard is the Qi standard.

[0010] [First Embodiment] This embodiment will be described with reference to the drawings. Figure 1 is a diagram showing an example of the configuration of a wireless charging system according to the first embodiment. This wireless charging system comprises a power transmission device 100, a power receiving device 200, and a charging cradle (Interface Surface) 300.

[0011] In the following, for the sake of brevity, the power receiving device 200 may be referred to as RX200 and the power transmitting device 100 as TX100. The detailed configurations of TX100 and RX200 will be described later using Figures 2 and 3.

[0012] The RX200 is an electronic device that receives power wirelessly from the TX100 and charges its internal battery when placed on the charging cradle 300. The TX100 is an electronic device that wirelessly transmits power to the RX200 when it is placed on the charging cradle 300. Since the charging cradle 300 constitutes part of the TX100, in the following, when the RX200 is "placed on the charging cradle 300", it may be referred to as "placed on the TX100". The spatial range in which the RX200 can receive power from the TX100 is schematically shown in Figure 1 by the area of ​​the dotted line frame 400. The RX200 and TX100 may have functions to perform applications other than wireless charging. For example, the RX200 is a smartphone, and the TX100 is an accessory device for charging the RX200's battery. However, this disclosure is not limited to this example.

[0013] Next, with reference to Figure 2, an example configuration of the power transmission device 100 will be described. Figure 2 is a functional block diagram showing an example configuration of the power transmission device 100. TX100 includes a control unit 101, a power supply unit 102, a power transmission unit 103, a first communication unit 104, a power transmission antenna (power transmission coil) 105, a memory 106, a resonant capacitor 107, a switch unit 108, a second communication unit 109, and a user interface unit 110. Hereinafter, the user interface will be referred to as UI. In Figure 2, each functional block element is shown as a separate entity, but any multiple functional block elements may be implemented as the same hardware module (for example, on the same chip).

[0014] The control unit 101 controls the entire TX100 by executing a control program stored in the memory 106. The control unit 101 also performs power transmission control, including communication for device authentication in the TX100. Furthermore, the control unit 101 can perform control for applications other than wireless power transmission. The control unit 101 is configured to include one or more processors, such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). Alternatively, the control unit 101 may be configured to include hardware 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 perform predetermined processing. The control unit 101 can perform processing to store information that should be stored during the execution of various processes in the memory 106, and can perform timing processing using a timer (not shown).

[0015] The power supply unit 102 supplies power to each functional block element. The power supply unit 102 includes, for example, a power connection circuit to the commercial power supply and a battery. The battery is charged by the power supplied from the commercial power supply.

[0016] The power transmission unit 103 converts the DC power or AC power input from the power supply unit 102 into AC power in the frequency band used for wireless power transmission, and inputs the converted AC power to the power transmission antenna 105 to generate electromagnetic waves for the RX200 to receive power. For example, the power transmission unit 103 is equipped with an inverter and converts the DC voltage supplied by the power supply unit 102 into an AC voltage using a switching circuit in a half-bridge or full-bridge configuration. The power transmission unit 103 includes a plurality of FETs (Field Effect Transistors) that constitute a bridge and a gate driver that controls the ON / OFF state of the plurality of FETs.

[0017] The power transmission unit 103 controls the intensity of the electromagnetic waves (transmitted power) output by adjusting the voltage (transmission voltage) or current (transmission current), or both, input to the power transmission antenna 105. The strength of the electromagnetic waves (strength of the transmitted power) is controlled by the magnitude of the transmission voltage or transmission current.

[0018] Alternatively, the power transmission unit 103 controls the intensity of the electromagnetic waves it outputs (power transmission) by adjusting the voltage, current, or both input to the inverter it has. The voltage input to this inverter will be referred to as the inverter input voltage below. The current input to this inverter will be referred to as the inverter input current below. The strength of the electromagnetic waves (strength of the power transmission) is controlled by the magnitude of the inverter input voltage or inverter input current.

[0019] Alternatively, the power transmission unit 103 controls the intensity of the electromagnetic waves (transmitted power) by adjusting the voltage, current, or both output from the inverter of the power transmission unit 103. The voltage output from this inverter will be referred to as the inverter output voltage below. The current output from this inverter will be referred to as the inverter output current below. The strength of the electromagnetic waves (strength of the transmitted power) is controlled by the magnitude of the inverter output voltage or inverter output current.

[0020] The power transmission unit 103 controls the output power of AC frequency electromagnetic waves so that it can start or stop power transmission by the power transmission antenna 105 or control the intensity of the electromagnetic waves to be output, based on instruction signals from the control unit 101. The power transmission unit 103 is also assumed to have the power supply capacity to output / supply 15 watts (W) of power to the charging section of the power receiving device 200 which complies with the WPC standard.

[0021] The first communication unit 104 is connected to the control unit 101 and the power transmission unit 103, and communicates with the RX200 for power transmission control based on the WPC standard. The first communication unit 104 performs frequency shift modulation of the electromagnetic waves output from the power transmission antenna 105 and transmits information to the RX200 for communication. The first communication unit 104 also demodulates the electromagnetic waves transmitted from the power transmission antenna 105, which have been modulated by the RX200, and obtains the information transmitted by the RX200. Communication by the first communication unit 104 is performed by superimposing a communication signal on the electromagnetic waves transmitted from the power transmission antenna 105. The first communication unit 104 performs so-called in-band communication.

[0022] Memory 106 can store information regarding the status of TX100 and RX200, in addition to the control program. This information includes the power transmission value, power reception value, etc. Information regarding the status of TX100 is acquired by the control unit 101. Information regarding the status of RX200 is acquired by the control unit of RX200 and can be received by the first communication unit 104 or the second communication unit 109, which will be described later.

[0023] The switch unit 108 is connected in parallel to the series circuit of the resonant capacitor 107 and the power transmitting antenna 105. The control unit 101 transmits a control signal to the switch unit 108 to control its ON / OFF state. The power transmitting antenna 105 is connected to the resonant capacitor 107. When the switch unit 108 is turned ON and short-circuited by the control signal from the control unit 101, the power transmitting antenna 105 and the resonant capacitor 107 form a series resonant circuit and resonate at a specific frequency fA. At this time, current flows through the closed circuit formed by the power transmitting antenna 105, the resonant capacitor 107 and the switch unit 108. On the other hand, when the switch unit 108 is turned OFF by the control signal from the control unit 101 and the circuit is opened, power is supplied to the power transmitting antenna 105 and the resonant capacitor 107 from the power transmitting unit 103.

[0024] The second communication unit 109 is connected to the control unit 101 and communicates with the RX200 using a standard different from the WPC standard. For example, the second communication unit 109 communicates with the RX200 using an antenna (not shown) different from the transmitting antenna 105. Examples of communication methods used by the second communication unit 109 include wireless LAN (Local Area Network), Bluetooth® Low Energy (BLE), and NFC (Near Field Communication). For BLE, any communication method compatible with Bluetooth standard version 4.0 or later is acceptable. The frequency band used for power transmission from the transmitting antenna 105 is different from the frequency band used for communication by the second communication unit 109. The second communication unit 109 performs so-called out-of-band communication.

[0025] Regarding communication between the TX100 and the RX200, the TX100 may selectively use one of several communication standards to communicate with the RX200. For example, the following communication configurations using multiple communication standards selectively are possible. • Communication based on the first standard (WPC standard) between the first communication unit 104 of TX100 and the first communication unit 204 of RX200 (see Figure 3). • Communication based on a second standard (a standard other than the WPC standard) between the second communication unit 109 of TX100 and the second communication unit 212 of RX200 (see Figure 3).

[0026] The UI unit 110 is connected to the control unit 101 and provides various outputs to the user. These outputs include screen displays, blinking and color changes of LEDs (Light Emitting Diodes), audio output from the speaker, and vibration of the TX100 unit. The UI unit 110 is implemented using an LCD panel, speaker, vibration motor, etc.

[0027] Next, an example configuration of the power receiving device 200 will be described with reference to Figure 3. Figure 3 is a functional block diagram showing an example configuration of the power receiving device 200. The RX200 includes a control unit 201, a UI unit 202, a power receiving unit 203, a first communication unit 204, a power receiving antenna 205, a charging unit 206, a battery 207, and a memory 208. The RX200 further includes a first switch unit 209, a second switch unit 210, a resonant capacitor 211, a second communication unit 212, and a third switch unit 213. In this embodiment, an example is shown in which the functional block elements in Figure 3 are individual elements, but any multiple functional block elements may be implemented as a single hardware module (for example, within the same chip).

[0028] The control unit 201 controls each functional block element of the RX200 by executing a control program stored in the memory 208. Furthermore, the control unit 201 can perform control for executing applications other than wireless power transmission. The control unit 201 is configured to include one or more processors such as a CPU or MPU. In addition, the control unit 201 can control the entire RX200 (for example, the entire smartphone) in cooperation with the OS (Operating System) it is running. Alternatively, the control unit 201 is configured to include hardware such as an ASIC, or array circuits such as an FPGA compiled to perform predetermined processing. The control unit 201 stores information that should be stored during the execution of various processes in the memory 208, and can also perform timing processing using a timer (not shown).

[0029] The UI unit 202 is connected to the control unit 201 and 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 RX200 unit. The UI unit 202 is implemented using an LCD panel, speaker, vibration motor, etc.

[0030] The power receiving unit 203 receives AC power (AC voltage and AC current) generated by electromagnetic induction based on electromagnetic waves radiated from the TX100's transmitting antenna 105 via the power receiving antenna (power receiving coil) 205. The power receiving unit 203 then converts the received AC power into DC power or AC power of a predetermined frequency and supplies power to the charging unit 206. The charging unit 206 charges the battery 207. The power receiving unit 203 includes a rectifier unit (rectifier, rectifier circuit) and a voltage control unit necessary for supplying power to the load in the RX200. The rectifier unit converts the AC voltage and AC current from the transmitting antenna, received via the power receiving antenna 205, into DC voltage and DC current. This DC voltage will be referred to as the rectifier unit output voltage below. This DC current will be referred to as the rectifier unit output current below. The voltage control unit converts the level of the DC voltage (rectifier unit output voltage) output by the rectifier unit to a predetermined level. The predetermined level is the DC voltage level at which the control unit 201 and the charging unit 206 can operate. The power receiving unit 203 supplies power from the charging unit 206 to the battery 207 for charging. The power receiving unit 203 is assumed to have the power supply capacity to output 15 watts (W) of power to the charging unit 206.

[0031] The first communication unit 204 communicates with the first communication unit 104 of the TX100 for power receiving control based on the WPC standard. The first communication unit 204 is connected to the power receiving antenna 205 and the control unit 201. The first communication unit 204 demodulates the electromagnetic waves input from the power receiving antenna 205 and acquires information transmitted from the TX100. The first communication unit 204 performs load modulation, amplitude modulation, or backscatter modulation on the input electromagnetic waves and superimposes a signal concerning the information to be transmitted to the TX100 onto the electromagnetic waves, thereby communicating with the TX100.

[0032] Memory 208 stores information regarding the status of TX100 and RX200, in addition to the control program. Information regarding the status of RX200 is acquired by the control unit 201. Information regarding the status of TX100 is acquired by the control unit 101 of TX100 and can be received by the first communication unit 204 or the second communication unit 212, which will be described later.

[0033] The second communication unit 212 is connected to the control unit 201 and communicates with the TX100 using a standard different from the WPC standard. For example, the second communication unit 212 communicates with the TX100 using an antenna different from the receiving antenna 205. Examples of communication methods used by the second communication unit 212 include wireless LAN, BLE, and NFC. For BLE, any communication method compatible with Bluetooth standard version 4.0 or later is acceptable. The frequency band used when receiving power with the receiving antenna 205 is different from the frequency band used by the second communication unit 212 for communication.

[0034] Regarding communication between the TX100 and the RX200, the RX200 may selectively use one of several communication standards to communicate with the TX100. For example, the following communication configurations using multiple communication standards selectively are possible. • Communication based on the first standard (WPC standard) between the first communication unit 104 of TX100 and the first communication unit 204 of RX200. • Communication between the second communication unit 109 of TX100 and the second communication unit 212 of RX200, based on a second standard (a standard other than the WPC standard).

[0035] The first switch unit 209 is located between the charging unit 206 and the battery 207 and is controlled by the control unit 201. The first switch unit 209 has the function of controlling whether or not to supply the power received by the power receiving unit 203 to the battery 207, and the function of controlling the magnitude of the load. When the first switch unit 209 is turned OFF and opened by the control unit 201, the power received by the power receiving unit 203 is not supplied to the battery 207. When the first switch unit 209 is turned ON and short-circuited by the control unit 201, the power received by the power receiving unit 203 is supplied to the battery 207.

[0036] In Figure 3, the first switch unit 209 is located between the charging unit 206 and the battery 207, but the first switch unit 209 may also be located between the power receiving unit 203 and the charging unit 206.

[0037] Alternatively, the first switch unit 209 may be positioned between the closed circuit formed by the receiving antenna 205, the resonant capacitor 211, and the second switch unit 210, and the receiving unit 203. In this case, the first switch unit 209 has the function of controlling whether or not to supply the power received by the receiving antenna 205 to the receiving unit 203.

[0038] Furthermore, although the first switch unit 209 is described as a single functional block element in the example of Figure 3, it is possible to implement the first switch unit 209 as part of the charging unit 206 or the power receiving unit 203. Moreover, this disclosure is not limited to a configuration in which the first switch unit 209 is inserted in series between the charging unit 206 and the battery 207; the first switch unit 209 may also be inserted in parallel between the charging unit 206 and the battery 207. In this case, when the first switch unit 209 is turned OFF and opened by the control unit 201, the power received by the power receiving unit 203 is supplied to the battery 207. When the first switch unit 209 is turned ON and short-circuited by the control unit 201, the power received by the power receiving unit 203 is not supplied to the battery 207.

[0039] On the input side of the power receiving unit 203, the second switch unit 210 is connected in parallel with the resonant capacitor 211. The resonant capacitor 211 is connected to the power receiving antenna 205 via the third switch unit 213. The second switch unit 210 and the third switch unit 213 are controlled by the control unit 201. The third switch unit 213 has the function of controlling whether or not to open the terminals of the power receiving antenna 205. When the control unit 201 turns the third switch unit 213 OFF, the terminals of the power receiving antenna 205 are open. When the control unit 201 turns the third switch unit 213 ON, the power receiving antenna 205 is connected to the power receiving unit 203 via the resonant capacitor 211.

[0040] When the control unit 201 turns on the third switch unit 213 and the second switch unit 210 turns on and short-circuits, the receiving antenna 205 and the resonant capacitor 211 form a series resonant circuit and resonate at a specific frequency fB. At this time, current flows through the closed circuit formed by the receiving antenna 205, the resonant capacitor 211 and the second switch unit 210, but no current flows to the receiving unit 203. On the other hand, when the second switch unit 210 turns off and the circuit is opened, the power received by the receiving antenna 205 and the resonant capacitor 211 is supplied to the receiving unit 203. Note that this disclosure is not limited to the example in Figure 3, and the second switch unit 210 may be placed between the receiving antenna 205 and the resonant capacitor 211. When the third switch unit 213 is ON and the second switch unit 210 is ON, the terminals of the receiving antenna 205 are short-circuited. Furthermore, the third switch unit 213 may be positioned between the resonant capacitor 211 and the power receiving unit 203.

[0041] In this wireless charging system, the TX100 and RX200 transmit wireless power between the transmitting antenna 105 and the receiving antenna 205 in accordance with the WPC standard. The WPC standard defines the agreed-upon load power level between the RX200 and TX100 as a value called Guaranteed Load Power (hereinafter referred to as "GP"). Load power is the power consumed by the load. For example, GP represents the power value at which the output from the RX200 to the load is guaranteed even if the coupling between the receiving antenna 205 and the transmitting antenna 105 weakens and the power transmission efficiency decreases due to a change in the relative positions of the RX200 and TX100. In this specification, the coupling state between the transmitting antenna (transmitting coil) 105 and the receiving antenna (receiving coil) 205 may also be referred to as the coupling state between the TX100 and RX200. The load of the RX200 is the charging unit 206, the battery 207, etc., and the value of GP corresponds to the power that is guaranteed to be output from the power receiving unit 203. Alternatively, the value of GP corresponds to the power that is guaranteed to be output from the rectifier unit of the power receiving unit 203. For example, let's assume that the value of GP is 5 (watts) and the positional relationship between the power receiving antenna 205 and the power transmitting antenna 105 changes. In this case, even if the power transmission efficiency decreases, the TX100 will perform power transmission control so that it can output 5 watts to the load of the RX200. Furthermore, GP is determined by negotiation between the TX100 and the RX200. Note that this disclosure is not limited to GP, and this embodiment can be applied to a configuration in which power transmission and reception are performed with power determined by negotiation between the TX100 and the RX200.

[0042] Furthermore, when transmitting power from TX100 to RX200, we consider the case where an object is present near TX100. In this case, the object is one that may affect the power transmission from TX100 to RX200, and is a different object (foreign object) from RX200. Electromagnetic waves for power transmission may affect the foreign object, potentially causing a temperature rise or destruction of the foreign object. In this disclosure, a foreign object is an object that is neither a part of the power receiving device and the product into which the power receiving device is incorporated, nor a part of the power transmitting device and the product into which the power transmitting device is incorporated, but which may generate heat when exposed to a power signal. Examples of foreign objects include paper clips and IC cards. Objects that are essential parts of the power receiving device and the product into which the power receiving device is incorporated, or the power transmitting device and the product into which the power transmitting device is incorporated, but which may unintentionally generate heat when exposed to the radio power transmitted by the power transmitting antenna, are not considered foreign objects.

[0043] The WPC standard specifies a method to suppress the temperature rise and damage of foreign objects by stopping power transmission when foreign objects are present. Specifically, the power transmission device 100 can detect the presence of foreign objects on the charging base 300. The Power Loss method is a method of detecting foreign objects by the difference between the power transmitted by TX100 and the power received by RX200. The Q-value measurement method is a method of detecting foreign objects by the change in the Quality Factor (also called Q-factor, quality coefficient, Q value, etc.) of the power transmission antenna 105 (power transmission coil) in TX100. Alternatively, the Q-value measurement method is a method of detecting foreign objects by the change in the Quality Factor of the resonant circuit including the power transmission antenna 105 and the resonant capacitor 107 in TX100. In this disclosure, the Quality Factor of the power transmission antenna 105 and the Quality Factor of the resonant circuit including the power transmission antenna 105 and the resonant capacitor 107 are referred to as the Quality Factor related to the power transmission antenna 105. However, the foreign objects detected by TX100 are not limited to objects located on the charging base 300. TX100 can detect foreign objects located in its vicinity. For example, TX100 can detect foreign objects located within its power transmission range.

[0044] Referring to Figure 4, we will explain foreign object detection based on the Power Loss method specified in the WPC standard. In Figure 4, the horizontal axis represents the power transmitted by TX100, and the vertical axis represents the power received by RX200. On the graph line shown by the straight line segment 1002, point 1000 corresponds to the first transmitted power value Pt1 and the first received power value Pr1, and point 1001 corresponds to the second transmitted power value Pt2 and the second received power value Pr2. On the same graph line, point 1003 corresponds to the third transmitted power value Pt3 and the third received power value Pr3. The foreign objects to be detected are conductive metal pieces, etc.

[0045] First, TX100 transmits power to RX200 at a first transmission power value Pt1, and RX200 receives power at a first reception power value Pr1. Hereafter, this state will be referred to as the Light Load state. Then, TX100 stores the first transmission power value Pt1 (for example, in memory 106). At this time, RX200 performs load control so that the power received is the minimum power. Alternatively, RX200 performs load control so that the power received is within a predetermined range or below a predetermined threshold. Here, in "power within a predetermined range" or "power below a predetermined threshold," "power" refers to power that is approximately 10% of the Reference Power, which will be described later. Furthermore, RX200 may disconnect the load from the receiving antenna 205 so that the received power is not supplied to the load (charging unit 206, battery 207, etc. in Figure 3). Alternatively, RX200 may control the load so that a predetermined power is supplied to the load. This can be achieved by controlling the first switch unit 209. Subsequently, RX200 notifies TX100 of the first received power value Pr1 by transmitting a signal relating to the first received power value Pr1 to TX100. Upon receiving the signal relating to the first received power value Pr1 from RX200, TX100 calculates the power loss between TX100 and RX200. The power loss at this time is Pt1-Pr1 (=Ploss1). TX100 can generate a calibration point (hereinafter abbreviated as CP) 1000 that shows the correspondence between Pt1 and Pr1.

[0046] Next, TX100 changes the transmission power value to the second transmission power value Pt2 and transmits power to RX200, which receives power at the second received power value Pr2. Hereafter, this state will be referred to as the Connected Load state (load connected state, maximum load state). Then, TX100 stores the second transmission power value Pt2 (for example, in memory 106). At this time, RX200 performs load control so that the power received is the maximum power. Here, "maximum power" is a power value close to the Reference Power, which will be described later. Alternatively, RX200 performs load control so that the power received is within a predetermined range or above a predetermined threshold. For example, RX200 connects the receiving antenna 205 to the load so that the received power is supplied to the load. These can be achieved by controlling the first switch unit 209. Next, RX200 notifies TX100 of the second power received value Pr2 by transmitting a signal related to the second power received value Pr2 to TX100. Upon receiving the signal related to the second power received value Pr2 from RX200, TX100 calculates the power loss between TX100 and RX200. The power loss at this time is Pt2-Pr2 (=Ploss2). TX100 can then generate CP1001, which shows the correspondence between Pt2 and Pr2.

[0047] TX100 performs linear interpolation between CP1000 and CP1001 to generate line segment 1002. Line segment 1002 shows the relationship between transmitted power and received power in a state in which no foreign objects are detected in the vicinity of TX100 and RX200 (hereinafter referred to as the first detection state). Based on line segment 1002, TX100 can estimate the power value that RX200 will receive when power is transmitted at a predetermined transmitted power in the first detection state. For example, consider the case where TX100 transmits power at a third transmitted power value Pt3. In this case, TX100 can estimate the third received power value Pr3 that RX200 will receive from point 1003 on line segment 1002, which corresponds to Pt3.

[0048] As described above, based on multiple combinations of the power transmission value of TX100 and the power reception value of RX200 measured while varying the load, the power loss between TX100 and RX200 according to the load can be determined. Furthermore, by interpolation processing from multiple combinations of power transmission and reception values, the power loss between TX100 and RX200 for all loads can be estimated. The calibration process performed by TX100 and RX200 to obtain the combination of power transmission and reception values ​​is called the "Power Loss method Calibration process." The Calibration process is also abbreviated as CAL. In addition, performing the Calibration process again after it has been executed once to update or add calibration points is called the Recalibration process, and is abbreviated as ReCAL.

[0049] Let's assume that after CAL processing using the Power Loss method, TX100 actually transmits power to RX200 at the third transmission power value Pt3, and TX100 receives a signal from RX200 regarding the received power value Pr3* (is notified of the received power value Pr3*). This signal regarding the received power value Pr3* is the Received Power data packet (mode0) specified in the WPC standard, but other messages may be used. Hereafter, the Received Power data packet (mode0) will be referred to as RP0. RP0 contains the value of the received power value Pr3*. TX100 calculates Pr3-Pr3* (=Ploss_FO) by subtracting the received power value Pr3* actually notified by RX200 from the received power value Pr3 in the first detection state. Ploss_FO can be estimated as the power consumed by foreign objects if they are present near TX100 and RX200, i.e., power loss. Hereinafter, the state in which a foreign object is detected as being present near the TX100 and RX200 will be referred to as the second detection state.

[0050] In the second detection state, TX100 compares the power loss Ploss_FO, which is estimated to have been consumed by the foreign object, with a predetermined threshold. If the value of the power loss Ploss_FO exceeds the threshold, TX100 can determine that a foreign object is present. Alternatively, TX100 obtains the third received power value Pr3 from RX200 in the first detection state and pre-calculates the power loss Pt3-Pr3 (=Ploss3) between TX100 and RX200.

[0051] Next, TX100 obtains the power received value Pr3* from RX200 in the second detection state and calculates the power loss Pt3-Pr3* (=Ploss3*) between TX100 and RX200 in the second detection state. Then, TX100 can estimate the power loss Ploss_FO using Ploss3*-Ploss3.

[0052] As described above, there are two methods for calculating Ploss_FO in the second detection state. • The first method for calculating Ploss_FO from Pr3-Pr3*. A second method for calculating Ploss_FO from Ploss3*-Ploss3.

[0053] This embodiment primarily describes the second method, but the contents of this embodiment can also be applied to the first method.

[0054] Next, with reference to Figure 5, we will explain foreign object detection based on the Q-value measurement method specified in the WPC standard. Figure 5(A) is a schematic circuit diagram illustrating the Quality Factor measurement method using the Q-value measurement method. The AC power supply 901 corresponds to the power supply that outputs AC power generated by the power transmission unit 103 of TX100. The power transmission antenna 902 corresponds to the power transmission antenna 105, and the capacitor 903 corresponds to the resonant capacitor 107. The power transmission antenna 902 and the capacitor 903 are connected in series. The voltage value V8 is a voltage value at a predetermined frequency generated by the power transmission unit 103 to operate the wireless power transmission system (wireless charging system). The voltage value V9 is the voltage value applied to the power transmission antenna 902. Here, it is assumed that TX100 can change the frequency related to the voltage value. Furthermore, voltage values ​​V8 and V9 are the voltage values ​​measured by TX100 when TX100 transmits Analog Ping (hereinafter referred to as "AP") or Digital Ping (hereinafter referred to as "DP") to RX200. Note that since voltage values ​​V8 and V9 are AC voltage values, their RMS values ​​may also be used.

[0055] Figure 5(B) shows an example of the measurement results of V9 / V8 against frequency, with a peak at 100 kHz. The horizontal axis represents frequency, and the vertical axis represents the voltage ratio "V9 / V8". Since V9 / V8 represents the Quality Factor related to the transmitting antenna 902, its value changes when an object is placed near the transmitting antenna 902. The change in Quality Factor differs depending on whether an object is placed on TX100, whether RX200 is placed on TX100, whether foreign matter (metal fragments, etc.) is placed on TX100, and whether RX200 and foreign matter are placed on TX100.

[0056] In the Negotiation phase, as defined in the WPC standard and described later, the TX100 receives a FOD Status data packet signal from the RX200. The FOD Status data packet includes the Reference Quality Factor Value and the Reference Resonance Frequency Value. The Reference Quality Factor Value is the Quality Factor that can be measured at the terminal of the power transmission antenna of the test TX100 when the RX200 is mounted on the test TX100 and no foreign objects are nearby. The Reference Resonance Frequency Value is as follows: it is the resonant frequency calculated from the inductance value that can be measured at the terminal of the power transmission antenna of the test TX100 when the RX200 is mounted on the test TX100 and no foreign objects are nearby. Using the Q-value measurement method, a threshold is set based on the Reference Quality Factor Value. Foreign object detection is performed by comparing this threshold with the Quality Factor obtained from the actually measured V9 / V8. Alternatively, a threshold can be set based on the Reference Resonance Frequency Value. Foreign object detection is performed by comparing this threshold with the resonance frequency, which is actually determined by measuring V9 / V8.

[0057] In this embodiment, the RX200 and TX100 communicate for power transmission and reception control based on the WPC standard. The WPC standard defines multiple phases, including the Power Transfer phase in which power transmission is performed and one or more phases prior to actual power transmission. Communication for necessary power transmission and reception control is performed in each phase. For example, foreign object detection using the Power Loss method is performed in the Power Transfer phase based on data obtained in the Calibration phase. Foreign object detection using the Q-value measurement method is performed before power transmission (before Digital Ping transmission and in the Negotiation phase or Renegotiation phase).

[0058] The WPC standard includes three phases prior to power transmission: the Selection phase, the Ping phase, and the Configuration phase. In addition, there are the Negotiation phase and the Calibration phase. The processing of each phase is described below.

[0059] During the Selection phase, the TX100 intermittently transmits Analog Pings to detect when an object is placed on the TX100's charging base. Analog Ping is a short-duration power signal applied to detect the presence of an object. However, this power signal does not activate the control unit of the power receiving device. For example, it detects when an RX200 or a conductive piece is placed on the charging base. The TX100 detects either or both the voltage and / or current values ​​of the transmitting antenna 105 when the Analog Ping is transmitted. If the voltage value falls below a threshold, or the current value exceeds a threshold, the TX100 determines that an object is present and transitions to the Ping phase. Alternatively, if the Quality Factor calculated from the voltage value satisfies a predetermined condition, or if the Quality Factor calculated from the current value satisfies a predetermined condition, the TX100 determines that an object is present and transitions to the Ping phase.

[0060] In the Ping phase, TX100 transmits a Digital Ping, which has a higher power output than Analog Ping. Digital Ping is a power signal that activates the control unit of RX200, which is mounted on top of TX100. RX200 notifies TX100 of the received voltage value. In this way, TX100 recognizes that the object detected in the Selection phase is RX200 by receiving a response from RX200 that has received the Digital Ping. Upon receiving notification of the received voltage value from RX200, TX100 transitions to the Configuration phase. Also, before transmitting Digital Ping, TX100 measures the Quality Factor related to the transmitting antenna 105, for example, using Analog Ping. This measurement result is used when performing foreign object detection processing using the Q-value measurement method. Note that depending on the version of the WPC standard, the Selection phase described above may be included as part of the Ping phase and referred to as the Ping phase.

[0061] During the Configuration phase, TX100 identifies RX200 and obtains device configuration information (capability information) from RX200. RX200 transmits an ID data packet and a Configuration data packet. The ID data packet contains the RX200's identification information (or identifier), and the Configuration data packet contains the RX200's device configuration information (capability information). Upon receiving the ID data packet and Configuration data packet signals, TX100 responds with an acknowledgment (ACK). The Configuration phase then ends.

[0062] In the Negotiation phase, the GP value is determined based on the GP value requested by RX200 and the power transmission capacity of TX100. TX100 also receives an FOD Status data packet from RX200, which includes the Reference Quality Factor Value and Reference Resonance Frequency Value. In the Q-value measurement method, the presence or absence of foreign matter is determined based on thresholds using the Reference Quality Factor Value and Reference Resonance Frequency Value. TX100 performs foreign matter detection processing using the Q-value measurement method according to the request from RX200. Furthermore, the WPC standard specifies a method where, after transitioning to the Power Transfer phase, the same processing as the Negotiation phase is performed again at the request of RX200. The phase in which these processes are performed after transitioning from the Power Transfer phase is called the Renegotiation phase.

[0063] In the Calibration phase, the Power Loss Calibration process (hereinafter referred to as "Power Loss Calibration Process") is performed based on the WPC standard. The RX200 also notifies the TX100 of a predetermined power received value, allowing the TX100 to make adjustments for efficient power transmission. The predetermined power received value is, for example, the power received under light load conditions or connected load conditions. The power received value notified to the TX100 is used for foreign object detection processing using the Power Loss method.

[0064] In the Power Transfer phase, the TX100 and RX200 perform control for starting and continuing power transmission, error handling, and stopping power transmission upon full charge. The TX100 and RX200 perform communication processing for these power transmission and reception control operations. For example, communication is performed by superimposing signals onto electromagnetic waves transmitted (radiated) from the transmitting antenna 105 or receiving antenna 205, which are used when wireless power transmission is performed according to the WPC standard. The range in which communication according to the WPC standard is possible between the TX100 and RX200 is the same as the transmission range of the TX100. Depending on the version of the WPC standard, the Calibration phase described above may also be referred to as the Power Transfer phase, as it is part of the Power Transfer phase.

[0065] Next, the functions of the control unit of TX100 will be described with reference to Figure 6. Figure 6 is a block diagram showing an example of the functional configuration of the control unit 101 of the power transmission device 100 (TX100). The control unit 101 includes a communication control unit 301, a power transmission control unit 302, a measurement unit 303, a setting unit 304, and a state detection unit 305.

[0066] The communication control unit 301 performs communication control with the RX200 based on the WPC standard via the first communication unit 104, or performs communication control with the RX200 via the second communication unit 109.

[0067] The power transmission control unit 302 controls the power transmission unit 103 to control the power transmission to the RX200.

[0068] The measurement unit 303 measures the power transmitted to the RX200 via the power transmission unit 103 and measures the average transmitted power per unit time. The measurement unit 303 also measures the Quality Factor related to the power transmission antenna 105. The measurement unit 303 also measures the temperature using temperature sensors placed at multiple locations on the TX100. The measurement unit 303 also measures a quantity (e.g., coupling coefficient) that represents the electromagnetic coupling state between the power transmission antenna 105 and the power receiving antenna 205. The quantity representing the electromagnetic coupling state, such as the coupling coefficient, may also be called a coupling state index. In this specification, measuring the coupling state index and correcting the coupling state index (by correcting the coupling coefficient as described later) to obtain the corrected coupling state index may be considered as calculating or determining the coupling state between the power transmission antenna 105 and the power receiving antenna 205.

[0069] The setting unit 304 calculates and sets the threshold for foreign object detection in the Q-value measurement method and the threshold for foreign object detection in the Power Loss method using the method described above. The setting unit 304 also calculates and sets the threshold for foreign object detection or the threshold for detecting misalignment between TX100 and RX200 based on, for example, the coupling state index between the transmitting antenna 105 and the receiving antenna 205 measured by the measurement unit 303. The setting unit 304 also calculates and sets the threshold for foreign object detection or the threshold for detecting misalignment between TX100 and RX200 based on, for example, the temperature of the power transmission device measured by the measurement unit 303.

[0070] The state detection unit 305 performs state detection between the TX100 and the RX200. For example, the state detection unit 305 detects foreign objects present between the TX100 and the RX200, and also detects misalignment between the transmitting antenna 105 and the receiving antenna 205. More specifically, state detection processing is possible based on the Power Loss method, Q-value measurement method, temperature measured in the TX100, and the electromagnetic coupling state (e.g., coupling coefficient) between the transmitting antenna 105 and the receiving antenna 205. The state detection unit 305 can perform foreign object detection and misalignment detection between the transmitting antenna 105 and the receiving antenna 205 using other methods. For example, in a TX100 equipped with NFC communication functionality, the state detection unit 305 performs state detection processing using the NFC standard's peer detection function. In addition to detecting the presence or absence of foreign objects and the electromagnetic coupling state between the transmitting antenna 105 and the receiving antenna 205, the state detection unit 305 can also detect changes in the state of the TX100. For example, the state detection unit 305 can detect an increase or decrease in the number of RX200s on the TX100.

[0071] The setting unit 304 sets a threshold that serves as a criterion for determining the presence or absence of foreign matter when the TX100 performs state detection. State detection can be, for example, based on the Power Loss method, the Q-value measurement method, state detection based on the temperature measured in the TX100, or state detection based on the coupling state index of the transmitting antenna 105 and the receiving antenna 205. The setting unit 304 can also set a threshold for determination necessary for state detection processing using other methods. Based on the threshold set by the setting unit 304 and the measurement results from the measurement unit 303, the state detection unit 305 can perform foreign matter detection processing and positional misalignment detection processing between the transmitting antenna 105 and the receiving antenna 205. For example, the state detection unit 305 can acquire data such as transmitted power, Quality Factor, temperature measured in the TX100, and coupling coefficient between the transmitting antenna 105 and the receiving antenna 205 as measurement results from the measurement unit 303.

[0072] The processes performed by the communication control unit 301, power transmission control unit 302, measurement unit 303, setting unit 304, and state detection unit 305 shown in Figure 6 can be implemented using programs executed by the CPU or other components of the control unit 101. Each process is executed in parallel according to an independent program, while maintaining synchronization between programs through event processing or the like. However, two or more of these processes may be incorporated into a single program.

[0073] Next, an example of the processing flow related to power transmission and reception control performed by TX100 and RX200 will be described. Figure 7 is a flowchart of an example of power transmission control processing performed by TX100. This processing is realized, for example, by the control unit 101 of TX100 executing a program read from memory 106. This processing may also be performed in response to the power being turned on to TX100, in response to the user of TX100 inputting a command to start a wireless power transmission application, or in response to TX100 being connected to a commercial power source and receiving power. This processing may also be started by other triggers.

[0074] In S1201, TX100 performs the processes defined as the Selection and Ping phases of the WPC standard and waits for RX200 to be placed. Specifically, TX100 repeatedly and intermittently transmits Analog Ping according to the WPC standard to detect objects within the power transmission range. For example, TX100 can detect when RX200 or conductive pieces are placed on the charging base 300. If TX100 detects the presence of an object within the power transmission range, it transmits a Digital Ping.

[0075] When TX100 receives a predetermined response to Digital Ping, it determines that the detected object is RX200 and that RX200 has been placed on the charging base 300. Here, the "predetermined response" is the Signal Strength (SIG) data packet transmitted by RX200. This packet includes a Signal Strength Value representing the signal strength of the signal received by RX200. The Signal Strength Value is calculated from the following parameters: the voltage output by the rectifier of the power receiving unit 203 measured by RX200 (rectifier output voltage), the voltage of the open circuit including the power receiving antenna 205 measured by RX200 (open circuit voltage), or the power received value measured by RX200.

[0076] Furthermore, before transmitting a Digital Ping, the TX100 measures the Quality Factor of the power transmission antenna 105. This measurement result is used when performing foreign object detection processing using the Q-value measurement method.

[0077] After the placement of the RX200 is detected, in S1202, the TX100 obtains (receives) identification information from the RX200 through the Configuration phase communication defined by the WPC standard. During the Configuration phase, the RX200 sends an Identification data packet (ID Packet) to the TX100. The ID Packet contains the Manufacturer Code and Basic Device ID, which are the identification information for each individual RX200, as well as information elements that can identify the version of the WPC standard it supports.

[0078] Furthermore, the RX200 sends a Configuration data packet to the TX100. The Configuration data packet contains the following capability information for the RX200. • Maximum Power Value or Reference Power, which is a value that identifies the maximum power that the RX200 can supply to a load. Information indicating whether the RX200 has WPC standard negotiation functionality. • A parameter used in frequency-shifted modulation, a communication modulation method used when the TX100 transmits information to the RX200. • Information indicating whether the RX200 supports out-of-band communication functionality.

[0079] Furthermore, TX100 may obtain identification information for RX200 by means other than the communication during the Configuration phase of the WPC standard. The identification information for each individual RX200 may be the Wireless Power ID. Alternatively, it may be any other identification information that can identify an individual RX200, such as the Bluetooth Address (hereinafter referred to as "BD_ADDR") unique to the RX200's second communication unit 212. BD_ADDR is an 8-byte address used in BLE. BD_ADDR is a Public Address defined in the BLE standard, indicating, for example, the manufacturer of the RX200 or the individual identification information of the BLE communication function (second communication unit 212). BD_ADDR may also be a Random Address.

[0080] Next, in S1203, TX100 determines the GP through negotiation with RX200 based on the request from RX200 and its own power transmission capacity. In S1203, the Negotiation phase of the WPC standard communication takes place. For example, RX200 notifies TX100 of the power value it requests by sending a Specific Request. TX100 determines whether to accept the request based on its own power transmission capacity and other conditions. If TX100 accepts the request, it sends an acknowledgment (ACK) to RX200; if it does not accept the request, it sends a negation (NACK) or NAK to RX200. The GP value determined through negotiation with RX200 will be the value requested by RX200 if TX100 accepts the request from RX200. If TX100 does not accept the request from RX200, the GP value may be a predetermined value as defined in the WPC standard (e.g., 5 watts). Furthermore, if the TX100 receives information indicating that the RX200 does not support the Negotiation phase (for example, S1302 described below), it will not perform Negotiation phase communication and will determine the GP value to a predetermined value. The predetermined value is, for example, a value specified in advance by the WPC standard (for example, 5 watts).

[0081] Furthermore, TX100 performs foreign object detection processing using the Q-value measurement method in accordance with requests from RX200. TX100 receives a FOD Status data packet from RX200. This packet includes the Reference Quality Factor Value and Reference Resonance Frequency Value mentioned above. Then, TX100 performs foreign object detection using the Q-value measurement method. This foreign object detection is performed based on the following information. • The Quality Factor and / or Resonant Frequency of the transmitting antenna 105, as measured by TX100 before the transmission of the Digital Ping. A threshold value based on the Reference Quality Factor Value and / or Reference Resonance Frequency Value received by the TX100 from the RX200.

[0082] Next, in S1204, TX100 and RX200 perform the Calibration phase processing (CAL processing) of the WPC standard. In the Calibration phase, TX100 performs CAL processing using the Power Loss method based on the determined Reference Power value or GP value. First, RX200 transmits a signal to TX100 containing information about the power received under light load conditions (hereinafter referred to as the first reference power received information). Light load conditions include, for example, a load disconnection state, a load condition in which the power received value of RX200 is below a first threshold, or a load condition in which the power received value of RX200 is within a predetermined range (hereinafter referred to as the "first range"). In this embodiment, the first reference power received information is assumed to be 500 milliwatts (however, the first reference power received information is not limited to 500 milliwatts). The first reference power received information is information included in the Received Power data packet (mode1) specified in the WPC standard, but other messages may be used. Hereafter, Received Power data packet (mode1) will be referred to as RP1. TX100 determines whether to accept the first reference power information based on the Control Error Value contained in the Control Error (CE) data packet received from RX200. If TX100 accepts the first reference power information, it sends an acknowledgment (ACK) to RX200. If TX100 does not accept the first reference power information, it sends a negative response (NAK) to RX200.

[0083] Next, the RX200 performs processing to transmit a signal to the TX100 containing information about the power received in a load-connected state (hereinafter referred to as the second reference power received information). The load-connected state is, for example, the maximum load state, the load state in which the transmitted power value is equal to or greater than the second threshold, or the load state in which the power received by the RX200 is the maximum power. Here, "maximum power" is power close to the Reference Power. Alternatively, the load-connected state is the load state in which the power received by the RX200 falls within a predetermined range (hereinafter referred to as the "second range"). Here, the second range is a range of power values ​​higher than the first range. In this embodiment, the second reference power received information is set to 15 watts (however, the second reference power received information is not limited to 15 watts). The second reference power received information is information included in the Received Power data packet (mode2) specified in the WPC standard, but other messages may be used. Hereinafter, the Received Power data packet (mode2) will be referred to as RP2. Based on the Control Error Value contained in the Control Error (CE) data packet received from RX200, TX100 determines whether to accept the second reference power information. If TX100 accepts the second reference power information, it sends an acknowledgment (ACK) to RX200. If TX100 does not accept the second reference power information, it sends a negative response (NAK) to RX200. TX100 then sends an acknowledgment (ACK) to RX200 in response to the second reference power information and completes the CAL process.

[0084] Through the CAL processing described above, TX100 can calculate the amount of power loss between TX100 and RX200 in light-load and load-connected states based on the power transmission value of TX100 and the power reception values ​​included in the first and second reference power reception information. Furthermore, TX100 can calculate the amount of power loss between TX100 and RX200 for all power transmission values ​​that TX100 can take by performing interpolation processing between multiple power loss values. All power transmission values ​​that TX100 can take refer to any power within the range where the power reception received by RX200 in this embodiment ranges from 500 milliwatts to 15 watts. Note that the CAL processing described above is not required.

[0085] Subsequently, in S1205, TX100 transmits power until the RX200's battery 207 is fully charged. In S1205, communication of the Power Transfer phase according to the WPC standard takes place. RX200 repeatedly sends Control Error data packets (hereinafter referred to as "CE packets") to TX100 at time intervals of t_interval. t_interval is a value defined in the WPC standard, for example, 250 milliseconds. The CE packets contain a request for how much to increase or decrease the transmitted power. Based on the received CE packets, TX100 adjusts the transmitted power by controlling the current or voltage of the transmitting antenna 105. In other words, the CE packets contain parameter data for adjusting the transmitted power. By repeating this process, power transmission at the appropriate power level according to RX200's requests is performed in near real-time.

[0086] When the battery 207 is fully charged, the RX200 sends an End Power Transfer data packet (hereinafter referred to as the "EPT packet") to terminate the Power Transfer phase. The RX200 may send an EPT packet for reasons other than full charge. Also, when the Power Transfer phase is completed, the TX100 stops supplying power for charging the RX200.

[0087] Furthermore, if TX100 fails to receive the next CE packet after a time t_timeout has elapsed since the last CE packet was received, it determines that RX200 has been removed from the charging cradle 300. In this case, TX100 terminates the Power Transfer phase. t_timeout is a value defined by the WPC standard, for example, 1500 milliseconds.

[0088] The RX200 may send packets other than CE packets to the TX100 during the Power Transfer phase. For example, there is a Charge Status data packet that notifies the TX100 of the status of the RX200's battery 207. This packet contains a Charge Status Value that indicates the percentage of charge of the battery 207. When the TX100 receives the Charge Status data packet, it notifies the user of the charging status by displaying text or a diagram based on the Charge Status Value, for example, using the UI unit 110. The TX100 may receive the Charge Status data packet at any time and may notify the user at any time of its choosing.

[0089] During the Power Transfer phase, the TX100 transmits power to the RX200 and performs foreign object detection using the Power Loss method. For example, the CAL process calculates the power loss between the TX100 and RX200 in the first detection state during power transmission from the difference between the transmitted power value and the received power value. The calculated power loss corresponds to the reference power loss in the absence of foreign objects. The TX100 then determines that the difference between the power loss measured between the TX100 and RX200 during power transmission after the CAL process and the reference power loss is greater than or equal to a threshold, and determines that it is in the second detection state. The TX100, having determined that it is in the second detection state, can suppress the transmitted power to suppress the temperature rise of the foreign object. Furthermore, the interface surface may be cooled to dissipate heat from the RX200 and the foreign object. The interface surface here refers to the flat part of the TX100's surface closest to the transmitting antenna.

[0090] Referring to Figure 8, an example of the processing flow related to power reception control performed by RX200 will be explained. This processing is achieved, for example, by the control unit 201 of RX200 executing a program read from memory 208.

[0091] In S1301, RX200 performs the processes defined as the Selection phase and Ping phase of the WPC standard and waits for itself to be placed on TX100. RX200 detects that it has been placed on TX100, for example, by detecting a Digital Ping from TX100.

[0092] When RX200 detects that it has been placed on TX100, in S1302 it sends a signal to TX100 containing its identification information via an ID Packet and a Configuration data packet. Note that the identification information of RX200 may be transmitted by a method other than the communication in the Configuration phase of the WPC standard. In addition, other identification information such as BD_ADDR may be used as long as it is information that can identify each individual RX200. Furthermore, in S1302, RX200 can also transmit information other than identification information to TX100.

[0093] Next, in S1303, RX200 transmits a signal to TX100 containing information about the power values ​​it requests, and negotiates with TX100 to determine the GP. In S1303, the Negotiation phase of the WPC standard communication takes place. RX200 transmits an FOD Status data packet to TX100. This packet includes the Reference Quality Factor Value and the Reference Resonance Frequency Value.

[0094] Next, in S1304, the RX200 and TX100 perform the Calibration phase (CAL processing) according to the WPC standard. The processing performed by the RX200 in this phase is as described above. Note that the CAL processing described above is optional.

[0095] Subsequently, in S1305, RX200 receives power until battery 207 is fully charged. The processing performed by RX200 in this phase is as described above. In the Power Transfer phase, RX200 and TX100 perform foreign object detection processing using the Power Loss method. In S1305, RX200 repeatedly sends CE packets at intervals of t_interval, and finally sends an EPT packet to TX100 to terminate processing.

[0096] Next, a method for measuring the coupling state index (coupling coefficient) between the power transmission antenna and the power reception antenna in the MPP (Magnetic Power Profile) defined by the Qi standard will be described. The MPP is adopted in the standard "Qi2" of the wireless power transmission standard "Qi". In the WPC standard, there are a BPP (Baseline Power Profile) that performs power transmission of 5 watts or less to RX200, an EPP (Extended Power Profile) that performs power transmission of 15 watts or less, and the above-mentioned MPP. Here, the power profile is a set of features that defines the compliance level of the power transmission device or the power reception device. The MPP has a function of accurately fixing the TX100 and the RX200 at a predetermined position. A plurality of means for accurately fixing the TX100 and the RX200 at a predetermined position can be considered. For example, the power transmission antenna (power transmission coil) of the TX100 and the power reception antenna (power reception coil) of the RX200 can be accurately opposed (directly opposed) by using the magnets built in the TX100 and the RX200 respectively. That is, in this case, the MPP can be said to be an extended function of the BPP and a profile (power profile) that uses magnets for alignment between the power transmission device and the power reception device. The magnet may be a permanent magnet or an electromagnet. When transmitting a large amount of power in the rapid charging mode, it is desirable for the environment to increase the power transmission efficiency and reduce the power loss.

[0097] <照 TX100 calculates (estimates or reckons) k, which represents the coupling state (inductive coupling factor) between TX100 and RX200 est using the following formula (1-1). k est =E 0xg α 0rx p+E 1xg α 1rx (1-1) Here, α 0rx =E 0gy / E 0gg and α 1rx =E1gy / E 1gg And,

number

[0098] Furthermore, the above-mentioned eigenfactor, E 0xg , E 1xg , E 0gy , E 0gg , E 1gy and E 1gg to, E abc This is expressed as follows. The eigencoefficients will be explained by describing a, b, and c below.

[0099] a is {0 or 1}, 0: The slope of linear curve fit. 1: The intercept of a linear curve fit. It means...

[0100] Furthermore, b is a description of the power transmission equipment. g: Power transmission equipment in system model x: General power transmission device It means...

[0101] Furthermore, c is a description of the power receiving device. g: Power receiving device of the system model y: General power receiving device It means...

[0102] Here, the "system model power transmission device" refers to the reference power transmission device. Hereafter, in this specification, the "system model power transmission device" will be referred to as the reference power transmission device. Similarly, the "system model power receiving device" refers to the reference power receiving device. Hereafter, in this specification, the "system model power receiving device" will be referred to as the reference power receiving device.

[0103] In other words, E 0gg and E 1gg These are characteristic coefficients that represent the characteristics when the reference power transmission device and the reference power reception device are placed opposite each other. These characteristic coefficients are calculated in advance by measurement, and their values ​​are stored in memory 208 by RX200.

[0104] Also, E 0xg and E 1xg These are characteristic coefficients that represent the characteristics when the reference power receiving device and the power transmitting device to be actually used are placed opposite each other. These characteristic coefficients are calculated in advance by measurement, and their values ​​are stored in memory 106 by TX100.

[0105] Also, E 0gy and E 1gy These are characteristic coefficients that represent the properties when the reference power transmission device and the power receiving device to be actually used are placed opposite each other. These characteristic coefficients are calculated in advance by measurement, and their values ​​are stored in memory 208 by the RX200.

[0106] Figure 9(a) is a diagram illustrating the power transmission antenna and power transmission device enclosure. The power transmission device enclosure (housing) contains the power transmission antenna (power transmission coil). In this specification, as shown in Figure 9(a), the distance from the bottom surface of the power transmission antenna (power transmission coil) to the interface surface (top surface, bottom surface) of the power transmission device enclosure is defined as dZ. PTX This is defined as follows. Therefore, dZ PTX This can be described as the distance between the power transmission antenna (power transmission coil) and the power transmission device enclosure.

[0107] Figure 9(b) is a diagram illustrating the receiving antenna and the receiving device enclosure. The receiving device enclosure (housing) encloses the receiving antenna (receiving coil). In this specification, as shown in Figure 9(b), the distance from the bottom surface of the receiving antenna (receiving coil) to the interface surface (top surface, bottom surface) of the receiving device enclosure is defined as dZ. PRX This is defined as follows. Therefore, dZ PRX This can be described as the distance between the receiving antenna (receiving coil) and the receiving device enclosure.

[0108] In the Qi standard, the dZ of the MPP reference power transmission device PTX The nominal value is 1.2 mm. Also, in the Qi standard, the dZ of the MPP reference power receiver. PRX The nominal value is 0.66 mm.

[0109] Also, V rect This is the output voltage after rectification in the RX200's rectifier circuit when the RX200 receives a Digital Ping. The RX200 is V rect After measuring, information regarding the measured value (information indicating the measured value) is transmitted to TX100.

[0110]

number

[0111] Also, V in This is the DC voltage input to the inverter of the TX100, as measured by the TX100, or the voltage output by the inverter of the TX100, as measured by the TX100.

[0112] α 0rx The RX200 holds E in memory 208 0gy and E 0gg Calculated by RX200, α1rx The RX200 holds E in memory 208 1gy and E 1gg It is calculated by the RX200. The RX200 is α 0rx and α 1rx The values ​​are stored in memory 208, and information about these values ​​(information indicating these values) is sent to TX100. α 0rx and α 1rx This is the ecosystem scaling coefficient.

[0113] E 0xg and E 1xg This is pre-stored in memory 106 by TX100.

[0114] The TX100 receives V from the RX200. rect Information regarding α 0rx Information regarding and α 1rx Information regarding the TX100 measurements

number

[0115] As described above, the TX100 is the same as the V measured by the RX200. rect The TX100 measured the following:

number

[0116] In the current Qi standard MPP, the TX100's dZ PTXThis is based on the premise that it is equivalent to 1.2 mm, and the scaling factor and k mentioned above est The calculation method is also designed under that premise. Therefore, the TX100's dZ PTX If the distance differs from 1.2 mm by a certain amount or more, the premise is broken, so k est This could potentially make it impossible to calculate accurately.

[0117] Therefore, below, the dZ of the TX100 PTX When the distance differs from 1.2 mm by a certain amount or more, k est A method for accurately calculating this will be explained using Figures 10 and 11.

[0118] Figure 10 is a flowchart showing an example of processing by TX100 according to the first embodiment. Figure 11 is a flowchart showing an example of processing by RX200 according to the first embodiment.

[0119] First, the RX200 is mounted on the TX100 (F1001, F1101). Then, the TX100 and RX200 perform the Ping phase processing described above (F1002, F1102).

[0120] Next, the RX200 calculates the coefficient (α) related to the selected or calculated (determined) coupling between the power receiving device information. 0rx and α 1rx ) and are transmitted to TX100 (F1103). Here, the power receiving device information refers to the dZ of the reference power transmission device used by the power receiving device to determine the coupling coefficients. PTXThis is information that can determine the coupling. The coupling coefficient is information used to calculate or determine the coupling state between TX100 and RX200, and may also be called information used for coupling state calculation, information related to coupling state calculation, etc. For example, RX200 should send an Identification Packet (hereinafter referred to as ID data packet) defined in the Qi standard, which includes power receiving device information, to TX100. In this case, even if the value of the Basic Device Identifier in the ID data packet is generated randomly, the dZ of the reference power transmission device PTX You can use a random value range determined for each instance. Also, RX200 is used, for example, in the newly defined dZ of a reference power transmission device. PTX A packet containing the above information may be sent to TX100. Furthermore, the power receiving device information and the coupling coefficient are transmitted in an MPP-Extended Identification Packet (Qi MPP Extended Identification, MPP-XID data packet). The MPP-Extended Identification Packet is defined in the Qi standard. During the Ping phase or Configuration phase described above, RX200 sends the MPP-Extended Identification Packet to TX100. This packet also contains the V measured by RX200. rect This also includes information about [the subject].

[0121] When TX100 receives power receiving device information and coupling coefficients from RX200 (YES in F1003), it proceeds to F1004.

[0122] In F1004, TX100, based on the power receiving device information received from RX200, determines the dZ of the reference power transmission device used by RX200 to select or calculate (determine) the coupling coefficient. PTX To obtain the TX100, for example, the power receiving device identification number and the dZ of its reference power transmitting device. PTXA list containing the dZ of the RX200's reference power transmission device (a predefined list of multiple reference power transmission devices) is kept internally (for example, in memory 106). When TX100 receives a packet from RX200 that allows it to identify RX200, such as an ID data packet, it uses the above list to identify the dZ of the RX200's reference power transmission device. PTX The RX200 directly determines or judges the dZ of the RX200's reference power transmission device. PTX By sending this to TX100, TX100 will enter dZ PTX The data may be obtained and determined or judged. Also, in F1004, TX100 is the dZ of the reference power transmission device of RX200. PTX and TX100 dZ PTX The two values ​​are compared, and if they are equivalent, the process proceeds to F1005 (NO at F1004). Here, equivalent values ​​may be the same for both values, or the absolute difference between the two values ​​may be within a predetermined range (e.g., within 0.1 mm, within 0.3 mm, etc.). In the following explanation, equivalent values ​​will be explained assuming that the two values ​​are the same. Also, TX100 uses these dZ PTX If they are not equivalent values, proceed to F1006 (YES in F1004). Here, these dZ PTX TX100 may proceed to F1006 when the conditions are equivalent and the correction derived from the coupling coefficients is effective. The conditions under which the correction derived from the coupling coefficients is effective will be explained later in <Correction Method According to the First Embodiment>.

[0123] In F1005, TX100 is expressed using equation (1-1) to represent the bond state k est Calculate the result and proceed to F1007.

[0124] In F1006, TX100 receives a coupling coefficient (α) from RX200. 0rx and α 1rx ) is corrected to represent the bond state k est Calculate and proceed to F1007. For example, TX100 uses the correction factor E agg / E ag’g as, k estmay be calculated. Here, E ag’g refers to the dZ of TX100 PTX and is a characteristic coefficient calculated or determined using a reference power transmission device and a reference power reception device having the same dZ PTX The term "same" means that the two dZs PTX may be identical, or the absolute value of the difference between the two dZs PTX may be within a predetermined range (for example, within 0.1 mm, within 0.3 mm, etc.). In the following description, "same" means that the two dZs PTX are identical. Also, the first digit a of the suffix of E is the same as the first digit of the suffix of the coefficient related to the coupling received by TX100 (0 or 1). Details of the correction method will be described in <Correction Method According to the First Embodiment> described later.

[0125] In F1007, TX100 transmits the calculated information on the coupling state to RX200 (F1007). Then, in F1008, TX100 executes control according to the calculated coupling state. "Control according to the calculated coupling state" means, for example, that TX100 has a plurality of resonance capacitors 107 (not shown), and TX100 may select an optimal resonance capacitor 107 according to the calculated coupling state from among the plurality of resonance capacitors. Additionally or alternatively, "control according to the calculated coupling state" means, for example, that TX100 may select a noise suppression circuit according to the calculated coupling state. Additionally or alternatively, "control according to the calculated coupling state" means, for example, that TX100 may predict the power that can be transmitted according to the calculated coupling state. Additionally or alternatively, "control according to the calculated coupling state" means, for example, that TX100 may select an optimal parameter for in-band communication according to the calculated coupling state.

[0126] In F1104, RX200 determines whether or not it has received information regarding the coupling state calculated by TX100 (F1104). If RX200 determines in F1104 that it has received information regarding the coupling state calculated by TX100 (YES in F1104), it proceeds to F1105. If RX200 determines in F1104 that it has not received information regarding the coupling state calculated by TX100 (NO in F1104), it returns to F1104. In F1105, RX200 performs control according to the calculated coupling state based on the received information. "Control according to the calculated coupling state" may, for example, mean that RX200 has multiple resonant capacitors 211 (not shown), and RX200 selects the optimal resonant capacitor 211 from among the multiple resonant capacitors according to the coupling state. Additionally or alternatively, "control according to the calculated coupling state" may mean, for example, that RX200 selects a noise suppression circuit according to the coupling state. Additionally or alternatively, "control based on calculated coupling state" may mean, for example, that the RX200 predicts the power that can be received based on the coupling state. Additionally or alternatively, "control based on calculated coupling state" may mean, for example, that the RX200 selects the optimal parameters for in-band communication based on the coupling state.

[0127] Note that the order of the TX100 and RX200 flows is not limited to the example described above. Also, the operations of F1003-F1008 and F1103-F1105 are performed during the Ping phase or Configuration phase.

[0128] Next, the correction method used in this embodiment and its effective range will be described below. Note that only the coefficient of the gradient of the linear curve fit will be described below. The coefficient of the intercept of the linear curve fit will be explained in the same or similar manner if the first suffix of E is changed from 0 to 1, so the explanation will be omitted.

[0129] <Correction method according to the first embodiment> The details of the correction process in F100 will be described below. For simplicity, a new notation will be introduced. The characteristic coefficient calculated or determined from the measured values measured using a certain power receiving device y and a certain power transmitting device x will be denoted as E(x, y). For example, E 0bc is denoted as E(b, c). Then, if TX100 is taken as x, the reference power receiving device as C, RX200 as y, and the reference power transmitting device used by RX200 as A, then α 0rx can be described as in the following formula (1-2) using this notation. α 0rx = E 0gy / E 0gg = E(A, y) / E(A, C) (1-2) Also, E 0xg can similarly be described as in the following formula (1-3). E 0xg = E(x, C) (1-3)

[0130] The coefficient of p in formula (1-1) can be described as in the following formula (1-4).

Equation

[0131] As the coefficient for calculating or determining k est representing the coupling state, originally E(x, y) is desired to be used, but due to the constraints of a practical system, formula (1-4) is used instead. For formula (1-4) to be used instead of E(x, y), for example, it is the case when the deviation from the reference system (E(A, C)) such that E(A, y) = mE(A, C), E(x, C) = nE(A, C), and E(x, y) = mnE(A, C) can be described is small enough. That is, it is premised that there is a correlation between TX100 and the reference power transmitting device A, and there is no guarantee that it is effective when the dZ PTX of the reference power transmitting device A used by the power receiving device and the dZ PTX of TX100 are different. Therefore, the dZ PTXIf the distance differs from 1.2 mm by a certain amount or more, the TX100 can ensure accuracy by correcting the coefficient obtained by formula (1-4) by the correction coefficient β.

[0132] The coefficient we actually want to use can be written as shown in equation (1-5) below.

number

[0133] Here, B is dZ of TX100 PTX Same dZ PTX This refers to a reference power transmission device that has E(B,y), where E(B,y) is a value that the power receiving device measures and calculates or determines in advance, and is a value that TX100 cannot retain. It is necessary for TX100 to perform a correction assuming that the power receiving device does not have E(B,y) available in order to ensure backward compatibility of the system. Therefore, it is necessary to determine β so that the corrected value of equation (1-4) is close to the value of equation (1-5). In this embodiment, the correction is performed by determining β so that the denominator of the right-hand side of equation (1-4) is the same as the denominator of the right-hand side of equation (1-5). Then, β can be expressed by the following equation (1-6), and the coefficient of p after correction (see equation (1-1)) is expressed by the following equation (1-7).

number

number

[0134] Here, E 0g’g TX100 dZ PTX Same dZ PTX These are the intrinsic coefficients of the gradient measured and calculated or determined using a reference transmission device and a reference reception device having the following characteristics: TX100 dZ PTX Same dZ PTXA reference power transmission device having the same characteristics as the TX100 can be said to have the same characteristics. Similarly, the intercept in equation (1-1) can also be corrected. If the correction coefficient for the intercept is β', then k representing the coupling state est This can be calculated or determined by the following formulas (1-8).

number

[0135] Here, E 1g’g TX100 dZ PTX Same dZ PTX These are the intrinsic coefficients of the intercept measured, calculated, or determined using a reference power transmission device and a reference power receiving device.

[0136] Using the right-hand sides of equations (1-4), (1-6), and (1-7), we calculate the range in which the correction coefficient β is effective. Dividing the right-hand side of equation (1-4) by the right-hand side of equation (1-5) yields the following equation (1-9).

number

[0137] Furthermore, by dividing the right-hand side of equation (1-7) by the right-hand side of equation (1-5), we can write it as shown in equation (1-10).

number

[0138] Then, |1-η0| and |1-η1| represent the effectiveness of the uncorrected coefficient and the effectiveness of the corrected coefficient, respectively (the smaller each is, the closer to the ideal). If the corrected coefficient is effective, the following equation (1-11) holds.

number

[0139] Here, if we let E(A,C) be a, then each coefficient can be expressed using the difference with a as shown in the following equations (1-12) to (1-15). a = E(A,C) (1-12) a + d1 = E(A, y) (1-13) a + d² = E(B, y) (1-14) a + d3 = E(B,C) (1-15)

[0140] The condition shown by equation (1-11) can be written as equation (1-16) below using equations (1-12) to (1-15).

number

[0141] In summary, the conditions shown by equations (1-11) and (1-16) can be written as follows: equation (1-17).

number

[0142] If the expression in the absolute value sign on the left side of the condition shown in equation (1-17) is 0 or greater, and the expression in the absolute value sign on the right side is 0 or greater, that is,

number

[0143] If the expression in the absolute value sign on the left side of the condition shown in equation (1-17) is less than or equal to 0, and the expression in the absolute value sign on the right side is also less than or equal to 0, that is,

number

[0144] If the expression in the absolute value sign on the left side of the condition shown in equation (1-17) is greater than or equal to 0, and the expression in the absolute value sign on the right side is less than or equal to 0, that is,

number

[0145] If the expression in the absolute value sign on the left side of the condition shown in equation (1-17) is less than or equal to 0, and the expression in the absolute value sign on the right side is greater than or equal to 0, that is,

number

[0146] If we reorganize the conditions shown in equations (1-18) to (1-21) as conditions for d2, we get the conditions shown in equations (1-22) and (1-23) below (however, for simplicity, we assume δ = d3 + d1d3 / a). If δ < 0, then d2 > d1 + δ (1 - 22) If δ > 0, then d2 <d1+δ (1-23)

[0147] In other words, the larger the absolute value of δ, the wider the range in which d2 can exist, and the wider the range in which the correction is effective.

[0148] Therefore, TX100 can calculate or determine E(A,y) from the coupling coefficients received from RX200, and use E(B,C) and E(A,C) held by TX100 to calculate δ by the following equation (1-24).

number

[0149] TX100 is, for example,

number

[0150] By performing the above control on the TX100 and RX200, the TX100 will control the dZ PTXThe reference power transmission device's dZ PTX Even when the coupling distance differs from 1.2 mm, it becomes possible to calculate a more precise coupling state between the TX100 and RX200. Furthermore, based on this more precise coupling state, the TX100 and RX200 can perform more appropriate control.

[0151] [Second Embodiment] In the first embodiment, dZ of TX100 PTX However, if it differs from the nominal value of 1.2 mm assumed in the current Qi standard's MPP, k est A method for calculating with high accuracy by correcting is described. The correction method according to the first embodiment corrects the coefficients related to the coupling by multiplying them by a correction coefficient. Specifically, this correction method is for TX100's dZ PTX dZ is not equivalent to PTX The portion calculated using a reference power transmission device with the TX100 dZ PTX Equivalent to dZ PTX Replace with the value calculated using a reference power transmission device that has [specific feature / function].

[0152] In this embodiment, the dZ of the reference power transmission device used by RX200 PTX and TX100 dZ PTX The TX100 retains the intrinsic coefficients calculated or determined from the measurement results when the two are considered equivalent, and performs correction using these intrinsic coefficients. The configuration and operation / processing in the second embodiment, other than the correction method, are the same as or similar to those in the first embodiment, so the explanation of anything other than the correction method is omitted. The correction method used in this embodiment is described below. In the following, only the coefficient of the gradient of the linear curve fit will be explained. The coefficient of the intercept of the linear curve fit will be explained in the same or similar way if the first suffix of E is changed from 0 to 1, so the explanation is omitted.

[0153] <Correction method according to the second embodiment> Hereafter, the same notation as in the correction method according to the first embodiment will be used. Similar to the first embodiment, the uncorrected coefficient can be written as shown in equation (1-4), and the coefficient that is actually to be used can be written as shown in equation (1-5).

number

number

[0154] Now, let's assume that the following assumption, shown in equation (2-1), holds true.

number

[0155] Here, T represents the reference power transmission device, and z, which is an argument to x and T, is the dZ of the power transmission device. PTX This is a related parameter, and g(z) is a function of z. This assumes that the distance dependence of the power transmission equipment can be expressed independently of other factors. In other words, when the eigencoefficient E is the dependent variable and z is the independent variable, the discrepancy between the curve obtained by linear regression or nonlinear regression and the measured value of the eigencoefficient is small.

[0156] Then, if we set the z of reference power transmission device A to a and the z of reference power transmission device B to b, we obtain the following relationships (2-2) and (2-3).

number

number

[0157] Here, "z=0" refers to a certain reference dZ. PTX This means that it has. Also, x(z=a) is the dZ of TX100. PTX The dZ of reference power transmission device A PTXIt means assuming a power transmission device when it is equivalent to. Also, x(z = b) is the dZ of TX100 PTX is the dZ of the reference power transmission device B PTX It means assuming a power transmission device when it is equivalent to.

[0158] Instead of E(x(b), C) for which the uncorrected coefficient is used, using E(x(a), C) calculated or determined in advance by TX100, and assuming that the value multiplied by the correction coefficient β is equivalent to Equation (1 - 5), β is obtained by the following Equation (2 - 4).

Equation

[0159] Then, β can be obtained as in the following Equation (2 - 5).

Equation

[0160] Also, a method of measuring or estimating E(x(a), C) using TX100 includes, for example, measuring E(x(z), C) by changing the distance z between TX100 and the reference power receiving device. And if a ≤ b (or a < b), for example, the method includes approximating E(x(z), C) as a function of z and estimating the approximate value when z = a as E(x(a), C). And TX100 may hold and use the approximate value in, for example, the memory 106. Also, if b < a (or b ≤ a), the method includes measuring and / or calculating E(x(a), C) when the distance between TX100 and the reference power receiving device is a. And TX100 may hold and use the measured and / or calculated value in, for example, the memory 106.

[0161] Note that TX100 may enable the correction of Equation (1 - 5) when, for example, the value calculated or determined using the ratio of E(B, C) and E(A, C) exceeds a threshold value.

[0162] By performing the above corrections, the TX100's dZ PTX The reference power transmission device's dZ PTX When the coupling distance differs from 1.2 mm, it becomes possible to calculate a more precise coupling state between the TX100 and RX200. Then, based on this more precise coupling state, the TX100 and RX200 can perform more appropriate control.

[0163] [Third Embodiment] In the first and second embodiments, the dZ of TX100 PTX However, if it differs from the nominal value of 1.2 mm assumed in the current Qi standard's MPP, k est This section explains a method for calculating with greater accuracy by correcting for this.

[0164] In this embodiment, a method for performing correction is provided that also takes into account the case where the interface surface of TX100 and the interface surface of RX200 are not parallel.

[0165] First, the model used in the third embodiment will be explained using Figure 12. In Figure 12, the interface surface of TX100 lies on the xy plane, and circle A1201 is a circle with radius a0 centered on the origin O, which models the coil, and it is assumed that a current I flows through circle A1201 (coil) during power transmission. Point P (A1202) is a point in the vicinity of circle A1201. The vector calculated from point P and the origin O is vector PO, the angle between the Z axis and vector PO is θ, and the norm of vector PO is r. Also, the unit vector in the same direction as vector PO is e r Let the unit vector in the x-axis direction be e x In this case, the unit vector e is orthogonal to both of these unit vectors. θ Constitute, (e x ,e θ ,e rLet it be assumed that an orthogonal basis is constituted by ( ). Also, let the vector calculated from point P and point Q on circle A1201 be vector PQ, and let its norm be R. Let the angle formed by vector QO calculated from point Q and the origin O and the x-axis be φ. Let the current in the infinitesimal interval on circle A1201 for an infinitesimal angle dφ from point Q be Ids. In the above model, when a circular current I flows, the magnetic flux density at point P (A1202) near circle A1201 can be obtained as follows using the Biot-Savart law. Here, point P is approximated as being located near circle A1201.

Number

Number

Number

Number

[0166] Figure 16 illustrates a model for the case where the angle between the interface surface (transmitting surface) of TX100 and the interface surface (receiving surface) of RX200 is not zero. The coil of TX100 (modeled as a circle) is defined as circle A1201 centered at the origin O. The Z-axis is defined as the axis passing through the origin O and perpendicular to circle A1201. The coil of the receiving device (modeled as a circle) is defined as circle A1601, centered at O' and having the same radius as circle A1201, tangent to circle A1201 at point A1603. This model assumes a case where alignment is achieved using magnets, etc., but the interface surfaces of TX100 and RX200 do not directly face each other due to the presence of foreign matter, etc. Here, the foreign matter differs from foreign matter in Qi and may be a non-metallic material such as plastic. Let θ be the angle between the vector O'O, calculated from the center O' of circle A1601 and the origin O, and the Z-axis. Vector A1602 is a basis vector e passing through point O'. r Therefore, the angle between the line passing through point A1603 and the center O' of circle A1601 and the line passing through point A1603 and the origin O (i.e., the angle between the interface surface of TX100 and the interface surface of RX200) is 2θ. Also, if we let Z' be the axis perpendicular to circle A1601 and passing through the center O' of circle A1601, then the basis vector e r The angle between the circle A1201 of TX100 and the Z' axis is θ. Therefore, when a current I flows through the circle A1201 of TX100, the magnetic flux density that affects the current in the coil of RX200, which is the circle A1601, can be calculated using equations (3-1) and (3-2) above as shown in equation (3-3) below.

number

[0167] Here, μ0 is the permeability of vacuum, a0 is the radius of circle A1201 and circle A1601, and r is dZ. PTX +dZ PRXLet K be the coupling coefficient when the angle between the interface surfaces of TX100 and RX200 is 0, and let K' be the coupling coefficient when the angle between the interface surfaces of TX100 and RX200 is 2θ. Then, the relationship between K and K' can be described as shown in equation (3-4) below.

number

[0168] The above K' is k est Therefore, k represents the coupling state between TX100 and RX200. estは、 The correction can be made as shown in equation (3-5) below.

number

[0169] Using the above correction, the TX100's dZ PTX The reference power transmission device's dZ PTX When the value differs from 1.2 mm, it becomes possible to calculate a more accurate coupling state between the TX100 and the RX200. Furthermore, using the above correction, the TX100 can calculate a more accurate coupling state between the TX100 and the RX200 even when the interface surface of the TX100 and the interface surface of the RX200 are not parallel.

[0170] The correction method according to this embodiment, which corrects the coupling coefficient in accordance with changes in magnetic flux density intensity, will be described below with reference to Figures 13, 14, and 15.

[0171] Figures 13 and 14 are flowcharts illustrating processing examples of TX100 according to this embodiment, each using a different method for estimating the angle θ. Figure 13 will be used to explain the case where TX100 estimates the angle θ using Signal Strength Value. Figures 14 and 15 will be used to explain the case where TX100 receives the angle θ from RX200.

[0172] <When estimating angle θ at the signal level> Figure 13 is a flowchart showing an example of processing by TX100 that employs a method of estimating the angle θ based on the signal level of the signal received from RX200. In this case, the processing of RX200 may be the same as that of RX200 in the first and second embodiments, and therefore, the explanation of RX200 is omitted.

[0173] First, the RX200 is mounted on the TX100 (F1301). Then, the TX100 and RX200 perform the Ping phase processing described above (F1302). Next, the TX100 receives a Signal Strength (SIG) data packet (F1303). This packet contains a Signal Strength Value representing the signal strength of the signal received by the RX200. Next, the TX100 receives power receiving device information and a coefficient related to coupling (α 0rx and α 1rx When the message is received (YES in F1304), proceed to F1305.

[0174] Next, in F1305, TX100 estimates the angle θ between the interface surface of TX100 and the interface surface of RX200 from the Signal Strength Value (received power), and proceeds to F1306. TX100 can maintain a correspondence table between Signal Strength Value and angle θ (for example, in memory 106) by transmitting power at various angles θ with a reference power receiving device. TX100 can then estimate the angle θ from the Signal Strength Value received from RX200 using this correspondence table.

[0175] In F1306, TX100 compares the estimated angle θ with a threshold. If the estimated angle θ is less than or equal to the threshold (YES in F1306), TX100 proceeds to F1308; if the estimated angle θ exceeds the threshold (NO in F1306), it proceeds to F1307. Here, the threshold can be set to 6°, for example, by correcting up to a second-order infinitesimal quantity (however, the threshold is not limited to 6°).

[0176] In F1307, TX100 calculates k representing the coupling state est for correction and proceeds to F1309. TX100 uses the estimated angle θ, the radius a0 of the coil, the dZ of the power receiving device determined by the standard PRX and the dZ held by TX100 PTX to calculate the sum (or based on the sum) r, and uses Equation (3-5) to calculate or determine k est . E 0xg and E 1xg may be values measured, calculated or determined using TX100 and a reference power receiving device, and α 0rx , α 1rx and p may be values received by TX100 from RX200 and values measured by TX100. Also, as shown in Equation (3-6) below, the correction of the first and second embodiments may be performed first, and then the correction according to this embodiment may be further performed.

Equation

[0177] In the above, E ag’g is the characteristic coefficient calculated or determined using a reference power receiving device and a reference power transmitting device having the same dZ PTX as the dZ of TX100. Also, E PTX is the characteristic coefficient calculated or determined using a reference power receiving device and using the dZ ax’g of TX100 as the dZ PTX of the reference power transmitting device used by RX200PTX These are eigenfactors calculated or determined based on values ​​that have been converted and measured or estimated. The first 'a' in the above E suffix is ​​either 0 or 1, where "0" represents the eigenfactor of the gradient and "1" represents the eigenfactor of the intercept.

[0178] In F1308, TX100 is expressed using equation (1-1) to represent the bond state k est Calculate the result and proceed to F1309.

[0179] In F1309, TX100 transmits information about the calculated coupling state to RX200. Then, in F1310, TX100 performs control according to the calculated coupling state. "Control according to the calculated coupling state" means, for example, that TX100 has multiple resonant capacitors 107 (not shown), and TX100 selects the optimal resonant capacitor 107 from among the multiple resonant capacitors according to the calculated coupling state. Additionally or alternatively, "control according to the calculated coupling state" means, for example, that TX100 selects a noise suppression circuit according to the calculated coupling state. Additionally or alternatively, "control according to the calculated coupling state" means, for example, that TX100 predicts the power that can be transmitted according to the calculated coupling state. Additionally or alternatively, "control according to the calculated coupling state" means, for example, that TX100 selects the optimal parameters for in-band communication according to the calculated coupling state.

[0180] If TX100 estimates the angle θ at the signal level, RX200 only needs to execute the process shown in the flowchart in Figure 11, so the explanation is omitted.

[0181] <When receiving the angle θ from the power receiving device> Figure 14 is a flowchart showing an example of processing by TX100, which employs a method of receiving angle θ from RX200 and using angle θ for correction. Figure 15 is a flowchart showing an example of processing by RX200 corresponding to Figure 14. However, the processing of TX100 is the same as up to F1002 in the flowchart shown in Figure 10 described in the first embodiment, and the processing of RX200 is the same as up to F1102 in the flowchart shown in Figure 11 described in the first embodiment, so these explanations are omitted.

[0182] In F1401, TX100 sends a packet to RX200 to inquire about its tilt from the horizontal (called a tilt information query packet), and then proceeds to F1402.

[0183] If RX200 receives a packet from TX100 requesting tilt information at F1501 (YES at F1501), it proceeds to F1502; otherwise, it proceeds to F1503.

[0184] In F1502, RX200 calculates or determines its tilt from the horizontal, sends a packet containing information about the tilt (referred to as a tilt information packet) to TX100, and proceeds to F1503. Here, RX200 can, for example, have an internal inertial measurement device (hereinafter referred to as IMU), and use the IMU to detect the direction of gravity and calculate or determine the tilt by how many degrees the interface surface is tilted from the direction of gravity.

[0185] If TX100 receives a tilt information packet from RX200 at F1402, it proceeds to F1403. Alternatively, TX100 may proceed to F1406 if it detects, through timer processing (not shown), that a certain period has elapsed since generating or transmitting a tilt information query packet.

[0186] In F1403, TX100 calculates or determines the angle θ based on the tilt information received from RX200. For example, assuming that TX100 is positioned perpendicular to the direction of gravity, angle θ may be calculated or determined as half the angle indicated by the tilt information. Alternatively, if TX100 has a built-in IMU, angle θ may be calculated or determined as half the difference between the angle between the interface surface of TX100 and the direction of gravity and the angle indicated by the received tilt information.

[0187] In F1404, TX100 determines whether the calculated or determined angle θ is below a certain threshold. If TX100 determines that the angle θ exceeds the threshold (NO in F1404), it proceeds to F1406; if the angle θ is below the threshold (YES in F1404), it proceeds to F1405. Here, the threshold may be set using the same approach as when estimating the angle θ at the signal level.

[0188] In F1405, TX100 is expressed using equation (1-1) to represent the coupling state, similar to F1308. est Calculate the result and proceed to F1407.

[0189] In F1406, TX100, like in F1307, represents the coupling state k est Calculate and correct the value, then proceed to F1407.

[0190] In F1407, TX100 transmits information about the calculated coupling state to RX200. Then, in F1408, TX100 performs control according to the calculated coupling state. "Control according to the calculated coupling state" means, for example, that TX100 has multiple resonant capacitors 107 (not shown), and TX100 selects the optimal resonant capacitor 107 from among the multiple resonant capacitors according to the calculated coupling state. Additionally or alternatively, "control according to the calculated coupling state" means, for example, that TX100 selects a noise suppression circuit according to the calculated coupling state. Additionally or alternatively, "control according to the calculated coupling state" means, for example, that TX100 predicts the power that can be transmitted according to the calculated coupling state. Additionally or alternatively, "control according to the calculated coupling state" means, for example, that TX100 selects the optimal parameters for in-band communication according to the calculated coupling state.

[0191] If the RX200 receives information about the calculated coupling state in F1503 (YES in F1503), it proceeds to F1504; if it does not receive information about the coupling state (NO in F1503), it returns to F1501.

[0192] In F1504, RX200 performs control according to the calculated coupling state based on the received information. "Control according to the calculated coupling state" may, for example, mean that RX200 has multiple resonant capacitors 211 (not shown), and RX200 selects the optimal resonant capacitor 211 from among the multiple resonant capacitors according to the coupling state. Additionally or alternatively, "control according to the calculated coupling state" may mean, for example, RX200 selecting a noise suppression circuit according to the coupling state. Additionally or alternatively, "control according to the calculated coupling state" may mean, for example, RX200 predicting the receivable power according to the coupling state. Additionally or alternatively, "control according to the calculated coupling state" may mean, for example, RX200 selecting the optimal in-band communication parameters according to the coupling state.

[0193] By performing the above correction, the TX100 can calculate a more accurate coupling state between the TX100 and the RX200 when the interface surface of the TX100 and the interface surface of the RX200 are not parallel. Furthermore, under the above conditions, the dZ of the TX100 PTX The reference power transmission device's dZ PTX When the coupling distance differs from 1.2 mm, it becomes possible to calculate a more precise coupling state between the TX100 and RX200. Then, based on this more precise coupling state, the TX100 and RX200 can perform more appropriate control.

[0194] [Other embodiments] Some (or possibly all) of the configurations in the above embodiments may be replaced with other configurations that perform similar functions, or omitted, and other configurations may be added. Furthermore, this disclosure is not limited to WPC standards and can be applied to various standards.

[0195] Furthermore, for example, the receiving device may possess some or all of the functions of the power transmission device (see, for example, Figure 6). Alternatively, the receiving device may perform some or all of the processes that the power transmission device should perform (see, for example, Figures 7, 10, 13, and 14).

[0196] Furthermore, the configurations in the above-described embodiments may be combined in any way appropriate.

[0197] Furthermore, the power transmission and receiving devices may be, for example, image input devices such as imaging devices (still cameras, video cameras, etc.) or scanners, or image output devices such as printers, copiers, or projectors. In addition, the power transmission and receiving devices may be storage devices such as hard disk drives or memory devices, or information processing devices such as personal computers (PCs), smartphones, or tablet devices.

[0198] Furthermore, the power receiving device may also be an information terminal device. For example, an information terminal device has a display unit that displays information to the user and is supplied with power received from a power receiving antenna. The power received from the power receiving antenna is stored in a power storage unit (battery), and power is supplied to the display unit from that battery. In this case, the power receiving device may also have a communication unit that communicates with other devices different from the power transmitting device. The communication unit may support communication standards such as NFC communication or 5th generation mobile communication systems (5G).

[0199] Furthermore, the power receiving device may be a vehicle such as an automobile. For example, an automobile acting as a power receiving device may receive power from a charger (power transmission device) via a power transmission antenna installed in a parking lot. Alternatively, an automobile acting as a power receiving device may receive power from a charger (power transmission device) via a power transmission antenna embedded in the road. Such an automobile supplies the received power to a battery. The battery's power may be supplied to a drive unit (motor, electric unit) that drives the wheels, or it may be used to drive sensors used for driving assistance or a communication unit that communicates with external devices. In other words, in this case, the power receiving device may have, in addition to wheels, a battery, motors and sensors driven using the received power, and a communication unit that communicates with devices other than the power transmission device. Furthermore, the power receiving device may have a compartment for accommodating people. For example, sensors may be used to measure the distance between vehicles or the distance to other obstacles. The communication unit may, for example, be compatible with the Global Positioning System (Global Positioning Satellite, GPS). Furthermore, the communication unit may support communication standards such as the fifth-generation mobile communication system (5G). Also, the vehicle may be a bicycle or a motorcycle.

[0200] Furthermore, the power receiving device may be a power tool, a home appliance, or the like. These power receiving devices may have a battery, as well as a motor driven by the power received from the battery. These devices may also have a notification means for notifying the remaining battery level, etc. Furthermore, these devices may have a communication unit that communicates with other devices different from the power transmitting device. The communication unit may support communication standards such as NFC or 5th generation mobile communication systems (5G).

[0201] Furthermore, the power transmission device may be an on-board charger that supplies power to mobile information terminal devices such as smartphones and tablets that support wireless power transmission within the vehicle. Such an on-board charger may be installed anywhere in the vehicle. For example, the on-board charger may be installed on the vehicle's console, on the instrument panel (dashboard), between passenger seats, on the ceiling, or on the doors. However, it is preferable not to install it in a location that would interfere with driving. In addition, although an on-board charger has been described as an example of a power transmission device, such chargers are not limited to those installed in vehicles, but may also be installed in transport vehicles such as trains, airplanes, and ships. In this case, the charger may also be installed between passenger seats, on the ceiling, or on the doors.

[0202] Alternatively, a vehicle such as an automobile equipped with an on-board charger may also serve as a power transmission device. In this case, the power transmission device has wheels and a battery, and uses the power from the battery to supply power to the power receiving device via a power transmission circuit and a power transmission antenna.

[0203] This disclosure can also be implemented 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 a process in which one or more processors in the computer of that system or device read and execute the program. Furthermore, one or more of the functions of the above-described embodiments can also be implemented by a circuit (e.g., an ASIC) that implements said one or more functions.

[0204] Furthermore, some of the processes described in this disclosure with reference to the flowchart may be implemented in hardware. For example, a dedicated circuit can be automatically generated on the FPGA from a program to implement each step by using a predetermined compiler. Alternatively, a Gate Array circuit may be formed in the same way as the FPGA and implemented in hardware.

[0205] Furthermore, RX200 may transmit capability information to TX100 indicating which one or more correction methods it supports from the correction method according to the first embodiment, the correction method according to the second embodiment, and the correction method according to the third embodiment. If TX100 is notified by RX200 that it supports multiple correction methods, it may notify RX200 which of the multiple correction methods should be used.

[0206] Furthermore, the following additional information is disclosed regarding the above embodiments.

[0207] [Note 1] A power transmission device that wirelessly transmits power to a power receiving device, A receiving means for receiving the first information from the power receiving device, A determination means for determining the coupling state based on the characteristics of a first reference power transmission device used by the power receiving device to determine the first information, the characteristics of a second reference power transmission device having the same characteristics as the power transmission device, and the first information, A power transmission device characterized by having the following features.

[0208] [Note 2] The receiving means receives identification information for identifying the power receiving device from the power receiving device, The power transmission device according to Appendix 1, characterized in that the determination means determines the first reference power transmission device from a plurality of predefined reference power transmission devices based on the identification information, and determines the characteristics of the first reference power transmission device based on the distance between the power transmission coil of the first reference power transmission device and the enclosure of the first reference power transmission device that encloses the power transmission coil.

[0209] [Note 3] The receiving means receives from the power receiving device second information relating to the distance between the power transmission coil of the first reference power transmission device and the enclosure of the first reference power transmission device that encloses the power transmission coil. The power transmission device according to Appendix 1 or 2, characterized in that the determination means determines the characteristics of the first reference power transmission device based on the distance indicated by the second information.

[0210] [Note 4] The power transmission device according to any one of the appendices 1 to 3, characterized in that the determination means corrects the first information based on the ratio of a coefficient representing the characteristics of the first reference power transmission device and a coefficient representing the characteristics of the second reference power transmission device.

[0211] [Note 5] The power transmission device according to Appendix 4, characterized in that the determination means corrects the first information when the value determined based on the ratio exceeds a threshold.

[0212] [Note 6] The power transmission device according to any one of the appendices 1 to 5, characterized in that the determination means determines the coupling state based on the characteristics of the power transmission device.

[0213] [Note 7] The power transmission device according to Appendix 6, characterized in that the determination means corrects the first information based on the distance between the reference power receiving device and the power transmission device used to determine the characteristics of the power transmission device.

[0214] [Note 8] The receiving means receives from the power receiving device second information relating to the distance between the power transmission coil of the first reference power transmission device and the enclosure of the first reference power transmission device that encloses the power transmission coil. The determination means determines the coefficient based on a measurement taken based on the power transmission device and the reference power receiving device at the same distance as the distance indicated by the second information, or estimates the coefficient from measurement values ​​taken based on the power transmission device and the reference power receiving device at multiple distances. The power transmission device according to Appendix 7, characterized in that the determination means corrects the first information based on the ratio of a coefficient representing the characteristics of the first reference power transmission device to a coefficient representing the characteristics of the second reference power transmission device, and the coefficient.

[0215] [Note 9] The power transmission device according to any one of the appendices 1 to 8, characterized in that the determination means corrects the first information based on the angle formed between the power receiving surface of the power receiving device and the power transmitting surface of the power transmission device.

[0216] [Note 10] The receiving means receives third information from the power receiving device regarding the tilt of the power receiving device from the horizontal, The power transmission device according to Appendix 9, characterized in that the determination means determines the angle based on the third information.

[0217] [Note 11] The power transmission device according to Appendix 9, characterized in that the determination means determines the angle based on the signal strength of the signal received from the power receiving device.

[0218] [Note 12] Power transmission coil It further possesses, The power transmission device according to any one of appendices 9 to 11, characterized in that the determination means further corrects the first information based on the radius of the power transmission coil.

[0219] [Note 13] Enclosure containing the aforementioned power transmission coil It further possesses, The power transmission device according to Appendix 12, characterized in that the determination means further corrects the first information based on the distance between the power transmission coil and the enclosure, and the distance between the power receiving coil of the reference power receiving device and the enclosure of the reference power receiving device that encloses the power receiving coil.

[0220] [Note 14] A method used by a power transmission device to wirelessly transmit power to a power receiving device, The first step is to receive information from the power receiving device, A step of determining the coupling state based on the characteristics of a first reference power transmission device used by the power receiving device to determine the first information, the characteristics of a second reference power transmission device having the same characteristics as the power transmission device, and the first information. A method characterized by having the following:

[0221] [Note 15] A program that causes a computer to perform the actions described in Appendix 14. [Explanation of Symbols]

[0222] 100 Power transmission equipment 101, 201 Control Unit 103 Power Transmission Section 105 Power transmission antenna 200 Power receiving equipment 203 Power Receiving Section 205 Receiving Antenna 303 Measuring part 304 Settings Section 305 State detection unit

Claims

1. A power transmission device that wirelessly transmits power to a power receiving device, A receiving means for receiving the first information from the power receiving device, A determination means for determining the coupling state based on the characteristics of a first reference power transmission device used by the power receiving device to determine the first information, the characteristics of a second reference power transmission device having the same characteristics as the power transmission device, and the first information, A power transmission device characterized by having the following features.

2. The receiving means receives identification information for identifying the power receiving device from the power receiving device, The power transmission device according to claim 1, wherein the determination means determines the first reference power transmission device from a plurality of predefined reference power transmission devices based on the identification information, and determines the characteristics of the first reference power transmission device based on the distance between the power transmission coil of the first reference power transmission device and the enclosure of the first reference power transmission device that encloses the power transmission coil.

3. The receiving means receives from the power receiving device second information relating to the distance between the power transmission coil of the first reference power transmission device and the enclosure of the first reference power transmission device that encloses the power transmission coil. The power transmission device according to claim 1, characterized in that the determination means determines the characteristics of the first reference power transmission device based on the distance indicated by the second information.

4. The power transmission device according to claim 1, characterized in that the determination means corrects the first information based on the ratio of a coefficient representing the characteristics of the first reference power transmission device and a coefficient representing the characteristics of the second reference power transmission device.

5. The power transmission device according to claim 4, characterized in that the determination means corrects the first information when the value determined based on the ratio exceeds a threshold.

6. The power transmission device according to claim 1, wherein the determination means determines the coupling state based on the characteristics of the power transmission device.

7. The power transmission device according to claim 6, characterized in that the determination means corrects the first information based on the distance between the reference power receiving device and the power transmission device used to determine the characteristics of the power transmission device.

8. The receiving means receives from the power receiving device second information relating to the distance between the power transmission coil of the first reference power transmission device and the enclosure of the first reference power transmission device that encloses the power transmission coil. The determination means determines the coefficient based on a measurement taken based on the power transmission device and the reference power receiving device at the same distance as the distance indicated by the second information, or estimates the coefficient from measurement values ​​taken based on the power transmission device and the reference power receiving device at multiple distances. The power transmission device according to claim 7, characterized in that the determination means corrects the first information based on the ratio of a coefficient representing the characteristics of the first reference power transmission device to a coefficient representing the characteristics of the second reference power transmission device, and the coefficient.

9. The power transmission device according to claim 1, characterized in that the determination means corrects the first information based on the angle formed between the power receiving surface of the power receiving device and the power transmitting surface of the power transmission device.

10. The receiving means receives third information from the power receiving device regarding the tilt of the power receiving device from the horizontal, The power transmission device according to claim 9, characterized in that the determination means determines the angle based on the third information.

11. The power transmission device according to claim 10, characterized in that the determination means determines the angle based on the signal strength of the signal received from the power receiving device.

12. Power transmission coil It further possesses, The power transmission device according to claim 9, characterized in that the determination means further corrects the first information based on the radius of the power transmission coil.

13. Enclosure containing the aforementioned power transmission coil It further possesses, The power transmission device according to claim 12, characterized in that the determination means further corrects the first information based on the distance between the power transmission coil and the enclosure, and the distance between the power receiving coil of the reference power receiving device and the enclosure of the reference power receiving device that encloses the power receiving coil.

14. A method used by a power transmission device to wirelessly transmit power to a power receiving device, The first step is to receive information from the power receiving device, A step of determining the coupling state based on the characteristics of a first reference power transmission device used by the power receiving device to determine the first information, the characteristics of a second reference power transmission device having the same characteristics as the power transmission device, and the first information. A method characterized by having the following:

15. A program for causing a computer to perform the method described in claim 14.

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