JP2021044939A - Power receiving device, method for controlling power receiving device, and program - Google Patents

Abstract

To provide a power receiving device that improves convenience in wireless power transmission, a method for controlling the same, and a program.SOLUTION: A power receiving device wirelessly receives power from a power transmitting device that performs processing to detect an object different from the power receiving device during power transmission, and the power receiving device transmits calibration information including the value of received power in the power receiving device as information used for the detection processing, receives, from the power transmitting device, an acceptance response indicating accepting the calibration information or a rejection response indicating not accepting the calibration information as a response to the calibration information, and when the rejection response is continuously received a predetermined number of times, performs control for changing the power received in the power receiving device.SELECTED DRAWING: Figure 7

Description

The present invention relates to a power receiving device, a method for controlling the power receiving device, and a program.

In recent years, technological development of wireless power transmission systems has been widely carried out. Patent Document 1 discloses a power receiving device and a power transmitting device conforming to a standard (WPC standard) established by the Wireless Power Consortium (WPC), a standardization body for wireless charging standards. Further, Patent Document 1 further states that, as a method for detecting foreign matter in a power transmission device, power is received when the difference between the actual power loss in the received power received from the power receiving device and the estimated power loss calculated in advance becomes equal to or more than a threshold value. A method for determining that a foreign substance different from the device has been detected is disclosed. Here, the estimated power loss is calculated based on the actual power loss in the received power in the light load state and the load connection state notified by the power receiving device.

Japanese Unexamined Patent Publication No. 2015-165716

The receiving device transmits the received power as a calibration reference value to the transmitting device in order to calibrate the estimation of the power loss by the transmitting device. Due to the characteristics of the power transmission device, the transmitted power may not be stable due to the power value at which the switching of the power transmission circuit occurs, and the calibration reference value is not accepted at such a power value. If the transmission device does not accept the calibration reference value, the power loss estimation is not calibrated near the reference value. Generally, in the received power that is far from the received power used for calculating the estimated power loss, the error between the actual power loss and the estimated power loss becomes large. Therefore, when power is transmitted as the received power, the accuracy of detecting foreign matter is lowered, and there is a possibility that charging may be stopped due to erroneous detection of foreign matter or the temperature may rise due to non-detection of foreign matter. As a result, various problems may occur in which convenience is reduced, such as charging stop due to erroneous detection and temperature rise due to the inability to detect existing foreign matter.

The present invention has been made in view of the above problems, and provides a technique for improving convenience in wireless power transmission.

As one means for achieving the above object, the power receiving device according to the present invention has the following configuration. That is, it is a power receiving device that wirelessly receives power from a power transmitting device that detects an object different from the power receiving device during power transmission, and receives power in the power receiving device as information used in the detection process performed by the power transmitting device. A transmitting means for transmitting calibration information including a power value, and a receiving means for receiving an acceptance response indicating acceptance of the calibration information or a rejection response indicating not accepting the calibration information from the power transmission device as a response to the calibration information. When the rejection response is continuously received by the receiving means a predetermined number of times, the receiving means has a control means for controlling to change the received power in the power receiving device.

According to the present invention, convenience in wireless power transmission can be improved.

The figure which shows the configuration example of the wireless charging system (wireless power transmission system). The block diagram which shows the configuration example of the power receiving device. A block diagram showing a configuration example of a power transmission device. A flowchart showing the processing executed by the power transmission device. The flowchart which shows the example of the power loss calibration process. A flowchart showing the processing executed by the power receiving device. The flowchart which shows the example of the flow of extended calibration reference value transmission. Operation sequence diagram of power transmission device and power reception device. (A) is a diagram showing a communication sequence of the calibration phase, and (B) is a diagram showing a communication sequence for device authentication.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. The following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiment, not all of the plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the attached drawings, the same or similar configurations are designated by the same reference numbers, and duplicate explanations are omitted.

[System configuration]
FIG. 1 shows a configuration example of a wireless charging system (wireless power transmission system) according to the present embodiment. In one example, this system includes a power receiving device 101 and a power transmitting device 102. Hereinafter, the power receiving device 101 may be referred to as RX, and the power transmitting device 102 may be referred to as TX. The RX is an electronic device that receives power from the TX and charges the built-in battery. The TX is an electronic device that wirelessly transmits power to the RX mounted on the charging stand 103. RX can receive power from TX in the range 104. An example of RX is a smartphone, and an example of TX is an accessory device for charging the smartphone. The RX and TX may be storage devices such as a hard disk device and a memory device, or may be information processing devices such as a personal computer (PC). Further, RX and TX may be, for example, an image input device such as an imaging device (camera, video camera, etc.) or a scanner, or an image output device such as a printer, a copier, or a projector. Further, the TX may be a smartphone. In this case, the RX may be another smartphone or a wireless earphone. Further, the RX may be an automobile. Further, the TX may be a charger installed on a console or the like in an automobile. Further, RX and TX may have a function of executing an application other than wireless charging.

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

In the WPC standard, the amount of power guaranteed when RX receives power from TX is defined by a value called Guaranteed Power (hereinafter referred to as "GP"). The GP is guaranteed to be output to a load (charging circuit, etc.) in the RX even if the positional relationship between the RX and TX fluctuates and the power transmission efficiency between the power receiving coil and the power transmission coil decreases. Indicates the power value. For example, when the GP is 5 watts, even if the positional relationship between the power receiving coil and the power transmission coil fluctuates and the power transmission efficiency drops, the TX controls the power transmission so that it can output 5 watts to the load in the RX. I do.

RX and TX according to this embodiment perform communication for power transmission / reception control based on the WPC standard and communication for device authentication. Here, communication for power transmission / reception control will be described. The WPC standard defines a plurality of phases including a Power Transfer phase in which power transmission is executed and a phase before power transmission is performed.

The phases before power transmission includes (1) Selection phase, (2) Ping phase, (3) Configuration phase, (4) Negotiation phase, and (5) Calibration phase.
(1) In the Selection phase, the TX intermittently transmits Analog Ping and detects that an object exists within the power transmission range (for example, a power receiving device 101, a conductor piece, or the like is placed on the charging stand 103). ..
(2) In the Ping phase, the TX transmits a Digital Ping and receives a response from the RX that has received the Digital Ping, thereby recognizing that the detected object is the RX.
(3) In the Configuration phase, RX notifies TX of identification information and ability information.
(4) In the Negotiation phase, the GP value is determined based on the GP value required by RX, the power transmission capacity of TX, and the like.
(5) In the calibration phase, RX notifies TX of the received power value based on the WPC standard, and TX makes adjustments for performing foreign matter detection processing during power transmission.

In the Power Transfer phase in which actual power transmission is executed, control is performed for continuation of power transmission and stop of power transmission due to an error or full charge.

TX and RX perform communication for power transmission / reception control by in-band communication in which signals are superimposed using the same antenna (coil) as wireless power transmission based on the WPC standard. The range in which in-band communication based on the WPC standard is possible between TX and RX is almost the same as the range in which power transmission is possible. That is, in FIG. 1, the range 104 represents a range in which wireless power transmission and in-band communication are possible by the power transmission / reception coils of TX and RX. In the following description, "mounted" RX means that the RX has entered the inside of the range 104, and includes a state in which the RX is not actually placed on the charging stand 103. It shall be muted.

The TX and RX may perform communication for power transmission / reception control (out-of-band communication) using an antenna (coil) different from that of wireless power transmission. As an example of communication using an antenna (coil) different from wireless power transmission, a communication method compliant with the Bluetooth (registered trademark) Low Energy standard can be mentioned. Further, it may be performed by another communication method such as a wireless LAN of the IEEE802.11 standard series (for example, Wi-Fi (registered trademark)), ZigBee, NFC (Near Field Communication). Communication using an antenna (coil) different from that of wireless power transmission may be performed at a frequency different from the frequency used in wireless power transmission.

In the present embodiment, the RX performs a challenge-response type communication using an electronic certificate with the TX prior to determining the value of the GP, and authenticates the TX as a device. That is, the RX communicates for device authentication, and based on the result of the device authentication, determines the GP required for the TX in the negotiation phase. For example, RX requires a TX with a successful device certification to have a GP of 15 watts, and a TX that does not have a GP of 5 watts. The GP is not limited to a combination other than 15 watts and 5 watts, and any value may be used as long as the GP with the TX for which the device authentication is successful is larger than the GP in the other case. That is, the RX ensures that power transmission / reception with a large GP is performed only with the TX that has succeeded in device authentication. In this way, by determining the GP based on the result of device certification, the GP can pass the prescribed test specified by the WPC standard, etc., and the large GP can be transmitted only from the TX, which is recognized as capable of transmitting power with the large GP. It can be able to receive power.

[Device configuration]
Subsequently, the configuration of the power receiving device 101 (RX) and the power transmitting device 102 (TX) according to the present embodiment will be described. It should be noted that the configuration described below is merely an example, and a part (in some cases, all) of the configurations described below may be replaced with or omitted from other configurations that perform similar functions. It may be added to the configuration described. Further, one block shown in the following description may be divided into a plurality of blocks, or the plurality of blocks may be integrated into one block.

(Device configuration)
Subsequently, the configurations of the power receiving device 101 (RX) and the power transmitting device 102 (TX) according to the present embodiment will be described. It should be noted that the configuration described below is merely an example, and a part (in some cases, all) of the configurations described below may be replaced or omitted with other configurations that perform similar functions. It may be added to the configuration described. Further, one block shown in the following description may be divided into a plurality of blocks, or the plurality of blocks may be integrated into one block.

FIG. 2 is a diagram showing a configuration example of the power receiving device 101 (RX) according to the present embodiment. In one example, the RX has a control unit 201, a battery 202, a power receiving unit 203, a detection unit 204, a power receiving coil 205, a communication unit 206, a display unit 207, an operation unit 208, a memory 209, a timer 210, and a charging unit 211. ..

The control unit 201 controls the entire RX by executing a control program stored in the memory 209, for example. In one example, the control unit 201 performs the control necessary for device authentication and power reception in RX. The control unit 201 may perform control for executing an application other than wireless power transmission. The control unit 201 includes one or more processors such as a CPU (Central Processing Unit) and an MPU (Micro Processing Unit), for example. The control unit 201 uses hardware dedicated to specific processing such as an integrated circuit (ASIC) for a specific application, or an array circuit such as an FPGA (field programmable gate array) compiled to execute a predetermined processing. It may be configured to include. The control unit 201 stores the information to be stored during the execution of various processes in the memory 209. Further, the control unit 201 can measure the time by using the timer 210.

The battery 202 supplies the entire RX with the power required for control, power reception, and communication. Further, the battery 202 stores the electric power received via the power receiving coil 205. In the power receiving coil 205, an induced electromotive force is generated by an electromagnetic wave radiated from the TX power transmission coil 305, and the power receiving unit 203 acquires the power generated in the power receiving coil 205.

The power receiving unit 203 acquires AC power generated by electromagnetic induction in the power receiving coil 205. Then, the power receiving unit 203 converts the AC power into DC or AC power having a predetermined frequency, and outputs the power to the charging unit 211 that performs a process for charging the battery 202. That is, the power receiving unit 203 supplies power to the load in RX. The above-mentioned GP is an electric energy that is guaranteed to be output from the power receiving unit 203.

The detection unit 204 detects whether or not the RX is placed in the range 104 that can receive power from the TX. The detection unit 204 detects, for example, the voltage value or the current value of the power receiving coil 205 when the power receiving unit 203 receives the digital ping according to the WPC standard via the power receiving coil 205. Then, the detection unit 204 determines that RX is placed in the range 104, for example, when the detected voltage value is lower than the predetermined voltage threshold value or when the detected current value exceeds the predetermined current threshold value. Can be.

The communication unit 206 communicates with the TX by in-band communication (communication in which signals are superimposed using the same antenna (coil) as wireless power transmission based on the WPC standard) to control communication based on the WPC standard as described above. I do. The communication unit 206 acquires the information transmitted from the TX by demodulating the electromagnetic wave input from the power receiving coil 205. The communication unit 206 communicates with the TX by superimposing the information to be transmitted to the TX on the electromagnetic wave by further load-modulating the electromagnetic wave. That is, the communication by the communication unit 206 may be superimposed on the power transmission from the power transmission coil 305 (FIG. 3) of the TX. Further, the communication unit 206 may perform out-of-band communication with the TX.

The display unit 207 presents information to the user by any method such as visual, auditory, and tactile. The display unit 207 notifies the user, for example, the state of RX and the state of the wireless power transmission system including TX and RX as shown in FIG. The display unit 207 includes, for example, a liquid crystal display, an LED (Light Emitting Diode), a speaker, a vibration generating circuit, and other notification devices.

The operation unit 208 has a reception function for receiving an operation on the RX from the user. The operation unit 208 includes, for example, a voice input device such as a button, a keyboard, and a microphone, a motion detection device such as an acceleration sensor and a gyro sensor, or another input device. A device in which the display unit 207 and the operation unit 208 are integrated, such as a touch panel, may be used.

The memory 209 stores various information. The memory 209 may store information obtained by a functional unit different from the control unit 201. The timer 210 measures the time by, for example, a count-up timer that measures the elapsed time from the start time, a countdown timer that counts down from the set time, and the like.

FIG. 3 is a diagram showing a configuration example of the power transmission device 102 (TX) according to the present embodiment. In one example, the TX includes a control unit 301, a power supply unit 302, a power transmission unit 303, a detection unit 304, a power transmission coil 305, a communication unit 306, a display unit 307, an operation unit 308, a memory 309, and a timer 310.

The control unit 301 controls the entire TX by executing a control program stored in the memory 309, for example. In one example, the control unit 301 performs device authentication in TX and control necessary for power transmission. The control unit 301 may perform control for executing an application other than wireless power transmission. The control unit 301 includes one or more processors such as a CPU and an MPU. The control unit 301 may be configured to include hardware dedicated to a specific process such as an ASIC, or an array circuit such as an FPGA compiled to execute a predetermined process. The control unit 301 stores the information to be stored during the execution of various processes in the memory 309. Further, the control unit 301 can measure the time by using the timer 310. The power supply unit 302 supplies the entire TX with the power required for control, power transmission, and communication. The power supply unit 302 is, for example, a commercial power supply or a battery.

The power transmission unit 303 converts the DC or AC power input from the power supply unit 302 into AC frequency power in the frequency band used for wireless power transmission. Further, by inputting the AC frequency power to the power transmission coil 305, an electromagnetic wave for receiving power from the RX is generated. The frequency of the AC power generated by the power transmission unit 303 is about several hundred kHz (for example, 110 kHz to 205 kHz).

Based on the instruction of the control unit 301, the power transmission unit 303 inputs AC frequency power to the power transmission coil 305 so as to output an electromagnetic wave for transmitting power to the RX from the power transmission coil 305. Further, the power transmission unit 303 controls the intensity of the electromagnetic wave to be output by adjusting the voltage (transmission voltage) or current (transmission current) input to the power transmission coil 305. Increasing the transmission voltage or transmission current increases the intensity of electromagnetic waves, and decreasing the transmission voltage or transmission current decreases the intensity of electromagnetic waves. Further, the power transmission unit 303 controls the output of the AC frequency power so that the power transmission from the power transmission coil 305 is started or stopped based on the instruction of the control unit 301.

The detection unit 304 detects whether or not an object exists in the range 104. The detection unit 304 detects, for example, the voltage value or the current value of the power transmission coil 305 when the power transmission unit 303 transmits the WPC standard Analog Ping via the power transmission coil 305. Then, the detection unit 304 can determine that an object exists in the range 104 when the voltage is lower than the predetermined voltage value or when the current value exceeds the predetermined current value. Whether this object is RX or other foreign matter is determined by the object being RX when a predetermined response is subsequently received by the communication unit 306 for Digital Ping transmitted by in-band communication. Is determined.

The communication unit 306 performs control communication based on the WPC standard as described above by in-band communication with the RX. The communication unit 306 modulates the electromagnetic wave output from the power transmission coil 305 and transmits the information to the RX. Further, the communication unit 306 demodulates the electromagnetic wave output from the power transmission coil 305 and modulated in the RX, and acquires the information transmitted by the RX. That is, the communication performed by the communication unit 306 is superimposed on the power transmission from the power transmission coil 305. Further, the communication unit 306 may perform out-of-band communication with the RX.

The display unit 307 presents information to the user by any method such as visual, auditory, and tactile. The display unit 307 notifies the user of, for example, information indicating the state of the TX and the state of the wireless power transmission system including the TX and RX as shown in FIG. The display unit 307 includes, for example, a liquid crystal display, an LED, a speaker, a vibration generating circuit, and other notification devices.

The operation unit 308 has a reception function for receiving an operation for TX from the user. The operation unit 308 includes, for example, a voice input device such as a button, a keyboard, and a microphone, a motion detection device such as an acceleration sensor and a gyro sensor, or another input device. A device in which the display unit 307 and the operation unit 308 are integrated, such as a touch panel, may be used.

As described above, the memory 309 stores various information. The memory 309 may store information obtained by a functional unit different from the control unit 301. The timer 310 measures the time by, for example, a count-up timer that measures the elapsed time from the start time, a countdown timer that counts down from the set time, and the like.

[Processing flow]
(Processing in power transmission equipment)
FIG. 4 is a flowchart showing a process executed by the power transmission device 102 (TX) in the present embodiment. This process can be realized, for example, by executing the program read from the memory 309 by the control unit 301 of the TX. Note that at least part of the following procedure may be implemented by hardware. The hardware in this case can be realized by, for example, using a predetermined compiler to automatically generate a dedicated circuit using a gate array circuit such as FPGA from a program for realizing each processing step. Further, in this process, in response to the TX power being turned on, in response to the TX user inputting a start instruction of the wireless charging application, or in response to the TX being connected to a commercial power source and receiving power supply. It can be done depending on what you are doing. In addition, this process may be started by another trigger.

In this process, the TX control unit 301 first waits for the RX to be mounted by the processes defined as the selection phase and the ping phase of the WPC standard via the communication unit 306 (S401). The communication unit 306 of the TX repeatedly intermittently transmits the WPC standard Analog Ping to detect an object existing within the power transmission range. Then, when the TX control unit 301 detects that an object exists within the power transmission range, it transmits a digital ping via the communication unit 306, and when there is a predetermined response to the digital ping, the detection is detected. It is determined that the object is RX and that RX is placed on the charging stand 103. When the TX control unit 301 detects the RX placement, it acquires identification information and capability information from the RX by communication in the configuration phase defined by the WPC standard via the communication unit 306 (S402). Here, the RX identification information includes the Manufacturer Code and the Basic Device ID. In addition, the RX capability information has an information element that can specify the version of the corresponding WPC standard, a Maximum Power Value that is a value that specifies the maximum power that the RX can supply to the load, and a Negotiation function of the WPC standard. Information indicating whether or not it is included is included. The TX may acquire the RX identification information and the capability information by a method other than the communication in the Configuration phase of the WPC standard. Further, the identification information may be any other identification information capable of identifying an individual RX, such as Wireless Power ID. Further, the ability information may include information other than the above.

Subsequently, the TX control unit 301 determines the RX and GP values by communication in the negotiation phase defined by the WPC standard via the communication unit 306 (S403). In S403, not only the communication in the Negotiation phase of the WPC standard but also other procedures for determining the GP may be executed. Further, when TX acquires information indicating that RX does not correspond to the Negotiation phase (for example, in F402), the TX does not perform communication in the Negotiation phase, and the GP value is predetermined (for example, in the WPC standard). ) It may be a small value.

After determining the GP, the TX control unit 301 performs calibration based on the GP (S404). Calibration is a process of calibrating the correlation between the transmission output value measured inside the TX and the received power value measured inside the RX with respect to the power transmitted by the TX to the RX. .. Specifically, the TX control unit 301 determines the power loss, which is the difference between the value of the power transmission output and the value of the power received, as the reference value of the power received from RX and the power transmission output at the time when the reference value is received. Estimate based on the value.
Further, in the calibration process, the transmitted power of TX and the received power of RX may be acquired in each of the two states having different RX. Then, using these two sets of transmitted power and received power, parameters for calibration may be calculated with respect to the received power or the transmitted power when actually being transmitted wirelessly. This parameter refers to the slope value and the intercept value when the correlation between the transmitted power and the received power is graphed by a linear function. Further, the combination used for calculating such a parameter is not limited to the set of transmitted power and received power, and may be a set of transmitted power and power loss, or a set of received power and power loss.

In calibration, WPC standard calibration phase communication is performed between TX and RX. FIG. 9A shows a communication sequence in the calibration phase of the WPC standard. In FIG. 9A, first, the RX communication unit 206 receives the Received Power (received) of mode 1, which is the received power information (hereinafter, referred to as the first calibration reference value) which is the first calibration reference value for the TX. (Power value) is transmitted (F901). The control unit 301 of the TX determines whether or not to accept the first calibration reference value received via the communication unit 306 based on the power transmission state of the own device. The communication unit 306 of the TX transmits ACK to RX when accepting the first calibration reference value, and NAK when not accepting the first calibration reference value (F902). Here, the TX accepts the notification when it determines that the power transmission state of its own device is stable. On the other hand, TX does not accept the notification when it determines that the power transmission state of its own device is unstable. When the RX communication unit 206 receives the NAK from the TX, the RX communication unit 206 transmits the Received Power of mode 1 again. On the other hand, when the RX communication unit 206 receives the ACK from the TX, the RX communication unit 206 transmits the received power information (hereinafter referred to as the second calibration reference value) of the mode 2 Received Power as the second calibration reference value to the TX. (F903). The control unit 301 of the TX determines whether or not to accept the second calibration reference value received via the communication unit 306 based on the power transmission state of the own device. Similar to F902, the communication unit 306 of TX transmits ACK to RX when accepting the second calibration reference value, and NAK to RX when not accepting the second calibration reference value (F904). When the RX communication unit 206 receives the NAK from the TX, the RX communication unit 206 transmits the Received Power of mode 2 again. When TX transmits ACK to RX, it calculates an estimated value of power loss in the section based on the received power of the first and second calibration reference values. On the other hand, if the TX cannot transmit the ACK to the RX as a response to the Received Power (mode 2) for a predetermined time after the end of the Negotiation phase (S403), it determines that the calibration has failed and stops the power transmission. The calibration may be performed by a method other than the WPC standard.

After the calibration is completed, the TX starts power transmission (S405). The power transmission is performed by the processing of the Power Transfer phase of the WPC standard, but may be performed by a method other than the WPC standard. Subsequently, TX communicates with RX for device authentication (S406). FIG. 9B shows a communication sequence for device authentication. The device authentication of the present embodiment is a challenge-response type device authentication using an electronic certificate, and RX authenticates TX. In addition, TX may authenticate RX, or both sides may authenticate the other party. The RX acts as an initiator that sends a challenge text to the TX, and the TX acts as a responder that encrypts the challenge text received from the RX and sends it to the RX. In FIG. 9B, the RX communication unit 206 first transmits a GET_DIGESTS message to the TX (F911). GET_DIGESTS is a message requesting information about the digital certificate held by the recipient (TX). The communication unit 306 of the TX transmits the DIGESTS to the RX in response to the GET_DIGESTS (F912). DIGESTS is information about a digital certificate owned by its sender (TX). Subsequently, the communication unit 206 of RX transmits a GET_CETTIFICATE message requesting detailed information about the digital certificate to TX (F913). The communication unit 306 of the TX transmits the CERTIFICATE to the RX in response to the GET_CERTIFICATE from the RX (F914). Then, the communication unit 206 of RX transmits a CHALLENGE message including the challenge text to TX (F915), and the communication unit 306 of TX transmits CHALLENGE_OUTH in which the challenge text received from RX is encrypted (F916). ). The RX control unit 201 determines that the device authentication was successful when the validity of CHALLENGE_AUTO received from the TX is confirmed, and determines that the device authentication has failed if the validity cannot be confirmed, and determines that the device authentication has failed. The authentication process ends. When the initiator (RX) receives a message indicating that the remote device (TX) does not support device authentication communication, the initiator (RX) determines that the remote device does not support device authentication. In addition, if the initiator (RX) does not receive a response during communication, it may retry by retransmitting a message for obtaining the response, or the other device does not support device authentication. It may be determined that there is. The RX may not communicate with the TX that does not support the device authentication for device authentication, and may determine that the result of the device authentication is not successful.

Subsequently, the TX control unit 301 redetermines the RX and GP values by communication in the negotiation phase defined by the WPC standard via the communication unit 306 (S407). In S07, since the device authentication is successful, the GP is determined to be a value larger than 5 watts (for example, 15 watts). The TX control unit 301 repeatedly executes the power transmission control process after the GP is redetermined (S408). When the TX control unit 301 receives the WPC standard End Power Transfer from the RX by the communication unit 306, the TX control unit 301 ends the processing in any processing phase and stops power transmission in accordance with the WPC standard. Then, the process returns to the Selection phase of S401. Since the End Power Transfer is transmitted from the RX even when the battery is fully charged, the process returns to the Selection phase of S401. During the power transmission control process of S408, the communication unit 306 of the TX receives the power transmission output change instruction and the extended calibration reference value. Here, the extended calibration reference value is information (calibration information) including the received power in the load connection state, which is the reference value for additional calibration for calculating the estimated value of the power loss. The TX control unit 301 changes the power transmission output based on the instructed change amount, triggered by the reception of the power transmission output change instruction. The power transmission output change instruction is a WPC standard Control Error, and includes a Control Error Value which is a value indicating the amount of voltage change. In Control Error Value, a positive value is stored when the transmission output is increased, a negative value is stored when the transmission output is decreased, and 0 is stored when the transmission output is not changed. Further, the TX control unit 301 executes the power loss calibration process when the extended calibration reference value is received. The power loss calibration process will be described later with reference to FIG. After the power transmission control process of S408, the control unit 301 of the TX determines whether or not to stop the power transmission during the power transmission (S409). For example, when RX is removed from the charging stand or TX detects a foreign substance (YES in S409), power transmission is stopped and the process is terminated.

Here, the power loss calibration process executed in S408 in FIG. 4 will be described. FIG. 5 is a flowchart showing an example of the power loss calibration process executed by the TX during the power transmission control process. This process can be realized, for example, by executing the program read from the memory 309 by the control unit 301 of the TX. In addition, at least a part of the following procedure may be realized by hardware. The hardware in this case can be realized by, for example, using a predetermined compiler to automatically generate a dedicated circuit using a gate array circuit such as FPGA from a program for realizing each processing step.

The TX control unit 301 executes the power loss calibration process when the extended calibration reference value is received from the RX. The TX control unit 301 determines whether or not to accept the received extended calibration reference value (S501). Here, the determination as to whether or not to accept can be made depending on whether or not the power transmission state of the own device is stable, and is not limited to this. For example, it may be determined that the power loss in the received power indicated by the extended calibration reference value is not accepted when it is separated from the calculated estimated value of the power loss by a predetermined value or more. When accepting the extended calibration reference value (YES in S501), the communication unit 306 of the TX sends an acknowledgment = ACK to the RX (S503), and the control unit 301 powers based on the received power indicated by the extended calibration reference value. The estimated loss value is calculated (S504), and the process is terminated. Here, the estimated value of the power loss is based on the power loss in the received power indicated by the received extended calibration reference value and the power loss in the received power indicated by the calibration reference value when the previous estimated value is calculated. Calculation is performed by linear interpolation, but the calculation is not limited to this. For example, the estimated value of power loss may be calculated by statistical analysis such as linear approximation or polynomial approximation based on at least one or more calibration reference values received after the calibration phase. In addition, these estimation methods may be selected depending on the number of available calibration reference values and the computational resources of TX. As a result, TX can calculate a highly accurate estimated value by performing statistical analysis using more calibration reference values when the computational resources are available, and when the computational resources are scarce. The calculation time required for calculation can be shortened by performing simple estimation such as linear interpolation. On the other hand, when the extended calibration reference value is not accepted (NO in S501), the communication unit 306 of TX transmits a rejection response = NAK to RX (S502), and ends this process.

[Processing in the power receiving device]
FIG. 6 is a flowchart showing a process executed by the power receiving device 101 (RX) in the present embodiment. This process can be realized, for example, by executing the program read from the memory 209 by the RX control unit 201. Note that at least part of the following procedure may be implemented by hardware. The hardware in this case can be realized by, for example, using a predetermined compiler to automatically generate a dedicated circuit using a gate array circuit such as FPGA from a program for realizing each processing step. Further, in this process, the RX user inputs the start instruction of the wireless charging application in response to the RX being activated by the power supply from the battery 202 or the TX in response to the RX power being turned on. Depending on it, it can be done. In addition, this process may be started by another trigger.

After the start of the process, the RX waits for the RX (own device) to be mounted on the TX by the process defined as the Selection phase and the Ping phase of the WPC standard via the communication unit 206 (S601). The RX control unit 201 detects that the RX has been placed on the TX, for example, by detecting the Digital Ping from the TX. When it is detected that the RX is mounted on the TX, the communication unit 206 of the RX transmits the identification information and the capability information to the TX by the communication of the Configuration phase defined by the WPC standard (S602). When the communication unit 206 of the RX transmits the identification information and the capability information, the control unit 201 determines the GP by the communication of the negotiation phase defined by the WPC standard (S603). Here, since the communication for device authentication is not performed, the RX control unit 201 negotiates so that GP = 5 watts. After the GP is determined, the RX communication unit 206 performs the WPC standard Calibration phase communication described in FIG. 9A based on the GP (S604).

When the calibration is completed, the RX starts receiving power by the communication of the Power transformer phase defined by the WPC standard (S605). When the power reception is started, the RX communication unit 206 performs the communication for device authentication described in FIG. 9B (S606). After that, the RX control unit 201 negotiates and redetermines the GP value as TX (S607). In S607, since the device authentication is successful, the GP is determined to be a value larger than 5 watts (for example, 15 watts). After the GP is redetermined, the RX control unit 201 repeatedly executes the power receiving control process (S608). In the power receiving control process, the RX controls the received power and performs the extended calibration reference value transmission process at a predetermined transmission timing (time interval). The extended calibration reference value transmission process will be described later with reference to FIG. 7. In the control of the received power, when the RX control unit 201 determines that the received power is insufficient with respect to the power consumption of the battery 202, the RX control unit 201 issues a transmission output change instruction including a positive value to the TX via the communication unit 206. Send. Further, when the RX control unit 201 determines that the power receiving input is higher than necessary with respect to the power consumption of the battery 202, the power transmission output change instruction including a negative value is transmitted to the TX via the communication unit 206. Further, when the RX control unit 201 determines that the power receiving input is appropriate for the power consumption of the battery 202, the power consumption is not changed, and the transmission output change instruction including 0 in the TX is issued via the communication unit 206. Send and proceed with processing. After the power receiving control process of S608, the RX control unit 201 determines whether or not to stop the power receiving during the Power transfer phase (S609). For example, when the RX is removed from the charging stand or the TX transmission stop is detected (YES in S609), the power reception is stopped and the process is terminated. When the RX control unit 201 detects that an error has occurred or that the battery has reached full charge, the RX control unit 201 transmits a WPT standard End Power Transfer via the communication unit 206. As a result, power transmission from the TX is stopped, and a series of processes for wireless charging is completed.

Here, the extended calibration reference value transmission process executed in S608 in FIG. 6 will be described. FIG. 7 is a flowchart showing the flow of the extended calibration reference value transmission process executed by the RX during the power reception control process. This process can be realized, for example, by executing the program read from the memory 209 by the RX control unit 201. In addition, at least a part of the following procedure may be realized by hardware. The hardware in this case can be realized by, for example, using a predetermined compiler to automatically generate a dedicated circuit using a gate array circuit such as FPGA from a program for realizing each processing step.

This process is repeatedly executed during the Power transfer phase at a predetermined timing. RX starts this flow when a predetermined time has elapsed after the completion of negotiation, but the present invention is not limited to this. For example, it may be started when the difference between the received power at the time when the negotiation is completed and the current received power changes by the threshold value or more, or the received power of the calibration reference value that received the ACK at the end and the current received power. It may be started when the difference from the electric power changes by a certain amount or more. As a result, the extended calibration reference value can be reliably transmitted when there is a change of a certain amount or more in the received power, that is, when the error of the estimated value of the power loss in TX becomes large.

In FIG. 7, the communication unit 206 of the RX transmits the extended calibration reference value including the current received power to the TX at the transmission timing of the extended calibration reference value (S701). After transmitting the extended calibration reference value, the RX communication unit 206 determines whether or not a rejection response has been received (S702). When an acceptance response is received for the extended calibration reference value (NO in S702), this flow ends without doing anything. On the other hand, when a rejection response is received with respect to the extended calibration reference value (YES in S702), the communication unit 206 determines whether or not the rejection response has been continuously received a predetermined number of times (S703). When it is determined that the rejection response has been continuously received a predetermined number of times, the RX control unit 201 performs control for changing the received power (S704). As an example, the RX control unit 201 performs control for reducing the received power. By lowering the received power, the probability that the TX will accept the extended calibration reference value can be increased. The RX control unit 201 may perform control to increase the received power. By increasing the received power, it is possible to increase the acceptance probability of the extended calibration reference value by the power transmission device without lowering the efficiency of power supply.

When the extended calibration reference value is accepted by the power transmission device, the power loss estimation is calibrated, and power reception can be safely continued while reducing the temperature rise due to false detection or non-detection of foreign matter. On the other hand, if it is determined that the number of consecutive receptions of the rejection response is less than the predetermined number, RX ends this processing without doing anything, and repeats the extended calibration reference value transmission processing (S701 to S704) until the acceptance response is received. To execute.

[System operation]
FIG. 8 shows an operation sequence of the power transmitting device 102 (TX) and the power receiving device 101 (RX). In the initial state, RX is not mounted on TX, and TX has sufficient power transmission capacity so that GP required by RX can transmit power.

The outline of the processing example shown in FIG. 8 will be described. First, in the first negotiation, GP is decided to be 5 watts, and TX starts power transmission. After the start of power transmission, the equipment certification of TX and RX was successful, and the GP was re-determined to 15 watts by re-execution of negotiation. After that, in order to change the received power in RX from 5 watts to 15 watts, RX transmits a transmission output change instruction to TX. However, in the process of changing the received power, an event occurs in which the extended calibration reference value including the current received power is not accepted by the TX for a predetermined number of times in a row. This can be an event caused by the properties of TX. For example, the TX transmission unit 303 is composed of a switching element (for example, a Field Effect Transistor, hereinafter referred to as an FET), and uses a switching circuit to convert a DC voltage or a current into an AC voltage or a current. The switching circuit includes a half-bridge circuit composed of two FETs and a full-bridge circuit composed of four FETs. The switching circuit of the transmission unit 303 is a half-bridge circuit and a full-bridge circuit depending on the magnitude of the transmitted power. It is widely known that it works by switching. Then, the power consumed by the switching circuit of the power transmission unit or the power transmitted by the power transmission coil (transmission power) may temporarily fluctuate greatly due to the operation, and the power transmission power may not be stable. For example, if a half-bridge circuit is used when the transmitted power is 3 watts or less and a full-bridge circuit is switched to when the transmitted power exceeds 3 watts, the power consumption value or transmitted power value of the switching circuit temporarily fluctuates significantly at the time of the switching. To do. In such a state where the transmitted power of the TX is not stable, the RX changes the received power until the extended calibration reference value is accepted.

In FIG. 8, the TX first waits for the object to be placed by the Analog Ping (F801). When RX is placed (F802), the Analog Ping changes (F803), and TX detects the placement of the object (F804). By the subsequent Digital Ping, RX detects that its own device is mounted on TX (F805, F806). In addition, TX detects that the placed object is RX by the response of Digital Ping. Subsequently, the TX acquires identification information and capability information from the RX by communication in the Configuration phase (F807). Next, since the device authentication is not successful at this point, GP = 5 watts is determined by the communication in the Negotiation phase (F808). Next, RX transmits a transmission output change instruction including a positive value to TX (F809). TX receives a transmission output change instruction including a positive value from RX, and increases the transmission output according to the instruction (F810). Subsequently, when the communication of the calibration phase is started, RX transmits the first calibration reference value to TX (F811). The TX receives the first calibration reference value of the received power = 500 milliwatts from the RX, and transmits an ACK because its power transmission state is stable (F812).

Next, RX transmits a transmission output change instruction including a positive value to TX (F813). TX receives a transmission output change instruction including a positive value from RX, and increases the transmission output according to the instruction (F814). The RX then transmits a second calibration reference value to the TX (F815). TX receives the second calibration reference value with the received power = 5 watts from RX, and since its own transmission state is stable, it calculates the estimated value of power loss based on the first and second calibration reference values. , ACK is transmitted to start the Power transfer phase (F816, F817).

Subsequently, TX and RX communicate for device authentication and succeed in this (F818). Since the device authentication was successful, GP = 15 watts was redetermined by the communication in the Negotiation phase (F819). When the GP is re-determined, the RX and TX start the power transmission control process and the power reception control process, respectively. When RX transmits a transmission output change instruction including a positive value to TX, TX increases the transmission output according to the instruction (F820, F821). Here, when the received power in RX rises to 10 watts, it is assumed that the power transmission state of TX becomes unstable due to, for example, switching of the mode of the power transmission circuit, temperature rise of the power transmission device, or other external factors. When the TX is unstable, the RX transmits an extended calibration reference value to the TX, and the TX transmits a NAK to the RX (F822, F823). After that, when NAK is returned a predetermined number of times in succession (three times in the example of FIG. 8) with respect to the extended calibration reference value transmitted by RX, RX gives an instruction to change the power transmission output to TX (F824 to F827). ). In the example of FIG. 8, RX shall instruct TX to reduce the transmission output by 1 watt.

The RX power change instruction is given when NAK is received a predetermined number of times in a row, but the present invention is not limited to this. For example, if a timeout is preset for the time from when RX starts transmitting the extended calibration reference value (after the first transmission) until the extended calibration reference value is accepted by TX, RX is the time until the timeout. And the number of times the calibration reference value can be transmitted is calculated based on the time interval for transmitting the extended calibration reference value. Then, the RX may determine whether or not to change the power based on the calculated number of times the calibration reference value can be transmitted. As a result, the extended calibration reference value can be transmitted with the same power until just before the timeout, and power reception can be continued without lowering the power reception efficiency.

Further, the RX according to the present embodiment stores the number of times of NAK received continuously until the calibration reference value is accepted, and determines whether or not to change the power based on the average value of the number of times. You may. This makes it possible to determine the timing of power change according to the characteristics of the power transmission device, and it is possible to continue receiving power without changing the received power.

Further, in the RX according to the present embodiment, the determination as to whether or not to give the power change instruction may be made based on the time. For example, RX starts time measurement when it first receives NAK. If the ACK response cannot be received by the elapse of the predetermined time, the transmitted power change instruction is transmitted to change the received power. As a result, the power change process can be performed at the timing when the response to the extended calibration reference value is not received.

Upon receiving the power transmission output change instruction, the TX lowers the power transmission output according to the instruction (F828). Then, after the received power in RX drops to 10 watts, the extended calibration reference value is transmitted again (F829). The TX calculates an estimated power loss based on the first calibration reference value and the extended calibration reference value (F830), but the TX transmits a NAK if it does not accept the received extended calibration reference value (F831). In response to this, the RXTX is instructed to change the power transmission output (F832). Upon receiving the power transmission output change instruction, the TX lowers the power transmission output according to the instruction (F833). Then, after the received power in RX drops to 6 watts, the extended calibration reference value is transmitted again (F834). The TX calculates an estimated power loss based on the first calibration reference value and the extended calibration reference value (F835), and transmits an ACK when accepting the received extended calibration reference value (F836).

In this way, the RX sends a power transmission output change instruction to change the received power, and the TX switches the mode of the power transmission circuit, the temperature of the TX rises, and other external factors cause unstable power transmission. Get out of the state. Then, TX accepts the extended calibration reference value as a new reference value and transmits ACK to RX. The RX according to the present embodiment may store the received power for which the calibration reference value is finally accepted, and change the received power so as to be the same as the stored value. As a result, the probability of accepting the calibration reference value by TX can be increased. Further, the RX according to the present embodiment may reduce the received power to the GP value or less determined by the negotiation before the device authentication is performed. As a result, it is possible to continue receiving power with safe power received. According to the operation described above, by changing the transmission power of the transmission device, the transmission device can exit the unstable transmission state and continue charging safely by accepting the extended calibration reference value. it can.

The RX according to the present embodiment transmits a power transmission output change instruction in order to change the received power, but the received power may be changed by negotiating again and lowering the GP. By lowering the GP by negotiation, it is possible to prevent the extended calibration reference value from being re-powered with unacceptable received power after the power is reduced once.

Further, the RX according to the present embodiment may transmit an End Power Transfer to the power transmission device to terminate the power supply once or request the power transmission device to negotiate again in order to change the received power. As a result, it is possible to prevent a time-out provided in the power transmission device, an erroneous detection of a foreign substance, or the like, the power supply is stopped at the discretion of the power transmission device, and the power is not resupplied.

As described above, according to the present embodiment, by changing the received power to a value at which the power transmission device can accept the calibration reference value, the calibration reference value is accepted by the power transmission device and the power loss estimation is calibrated. By calibrating the power loss estimation, the accuracy of foreign matter detection is improved, false detection and non-detection of foreign matter can be suppressed, and power can be received safely.

(Other embodiments)
The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by the processing to be performed.
It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

The invention is not limited to the above embodiments, and various modifications and modifications can be made without departing from the spirit and scope of the invention. Therefore, a claim is attached to make the scope of the invention public.

101 power receiving device, 102 power transmission device, 103 charging stand

Claims (12)

A power receiving device that wirelessly receives power from a power transmitting device that detects an object different from the power receiving device during power transmission.
A transmission means for transmitting calibration information including a received power value in the power receiving device as information used for the detection process performed by the power transmitting device, and a transmission means.
As a response to the calibration information, a receiving means for receiving an acceptance response indicating acceptance of the calibration information or a rejection response indicating not accepting the calibration information from the power transmission device.
When the rejection response is continuously received a predetermined number of times by the receiving means, the control means for controlling to change the received power in the power receiving device and the control means.
A power receiving device characterized by having. The power receiving device according to claim 1, wherein the transmitting means transmits the calibration information at predetermined time intervals. The predetermined number of times is set based on the preset time from the first transmission of the calibration information by the transmission means to the acceptance of the calibration information by the power transmission device and the predetermined time interval. The power receiving device according to claim 2, further comprising a determining means for determining. 1 or claim 1, further comprising a determining means for determining the predetermined number of times based on the number of rejected responses received consecutively before the acceptance response is received by the receiving means. 2. The power receiving device according to 2. The control means receives the rejection response a predetermined number of times in succession by the receiving means, or the acceptance response even after a predetermined time has elapsed from the first reception of the rejection response by the receiving means. The power receiving device according to claim 1, wherein when the power is not received, control is performed to change the received power. The control means is characterized by performing control for changing the received power in the power receiving device so as to be the received power value included in the calibration information corresponding to the acceptance response received by the receiving means. The power receiving device according to any one of claims 1 to 5. The control means is guaranteed when the power receiving device receives power from the power transmitting device, which is determined between the power receiving device and the power transmitting device before the calibration information is first transmitted by the transmitting means. The power receiving device according to any one of claims 1 to 5, wherein the power receiving device is controlled to change the power received so as to be equal to or less than the value of the power. The control means is characterized in that, when the rejection response is continuously received by the receiving means a predetermined number of times, the control means controls to change the received power in the power receiving device until the acceptance response is received. The power receiving device according to any one of claims 1 to 5. The power receiving device according to claim 8, wherein the control means requires the power transmission device to reduce the power transmission output as the control. The power receiving device according to claim 8, wherein the control means requires the power transmission device to increase the power transmission output as the control. When the rejection response is continuously received by the receiving means a predetermined number of times, the negotiating means for negotiating with the power transmitting device the power guaranteed when the power receiving device receives power from the power transmitting device is further provided. Have and
The method according to any one of claims 1 to 5, wherein the control means controls the value of the power determined by the negotiation by the negotiation means to change the received power in the power receiving device. Power receiving device. The method according to any one of claims 1 to 5, wherein when the receiving means receives the rejection response a predetermined number of times in a row, the control means instructs the power transmission device to stop power transmission. Power receiving device.

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