JP2014212663A - Power transmission apparatus, power reception apparatus, and method and program therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve transmission efficiency by appropriately detecting foreign matter between a power transmission apparatus and a power reception apparatus and performing power transmission when a positional relationship between the power transmission apparatus and the power reception apparatus is appropriate.SOLUTION: The power transmission apparatus, transmitting electric power to the power reception apparatus, intermittently performs transmission of electric power by radio. The power transmission apparatus, during intermittent power transmission, selects either of a first power transmission system including detection of a load-modulated signal according to an ID by the power transmission apparatus relative to transmitted electric power or a second power transmission system including modulation of electric power before power transmission according to the predetermined ID so that the power reception apparatus detects the predetermined ID, and operates according to the selected power transmission system.

Description

  The present invention relates to a power transmission device, a power reception device, a method thereof, and a program.

  Since MIT (Massachusetts Institute of Technology) conducted a field experiment of wireless power transmission by magnetic resonance in 2007, wireless power transmission technology has been widely researched and developed. In addition, wireless power transmission is used in combination with wireless communication, and has attracted attention as a technology aiming for complete wireless transmission (Non-Patent Document 1). Further, in recent years, wireless power transmission technology is spreading in various fields such as charging / transmission of electric vehicles and hybrid vehicles, and charging of small devices such as smartphones. For example, Patent Document 1 describes a power transmission management device that transmits power to a vehicle.

JP 2013-38924

"Developed technology to transmit power wirelessly, lighting 60W light bulb in experiment", Nikkei Electronics, No. 966, December 3, 2007

  When considering the safe operation of a wireless power transmission system, especially in systems that can transmit power even when the distance between the power transmitting device and the power receiving device is long, such as the magnetic resonance method, objects that can exist in the transmittable range Consideration is necessary. That is, it is necessary to prevent power transmission to a foreign object other than the power transmission target and other unauthenticated devices as much as possible within the power transmission range of the power transmission device. In addition, it is necessary to suppress heat generation or the like due to a reduction in efficiency because the power receiving device is arranged at an appropriate position as a relative positional relationship for the power transmitting device and the power transmitting device transmits power only when the power receiving device is in an appropriate positional relationship.

  Patent Document 1 discloses a method in which authentication between a power transmission device and a power reception device is performed before power transmission by the power transmission device, and the power transmission supplied by the power transmission device is confirmed to match the power received by the vehicle to continue power transmission. Have been described. However, when this method is used, high power is transmitted and received immediately after the authentication between the power transmitting apparatus and the power receiving apparatus is completed. Therefore, even when the positional relationship between the power transmission device and the power reception device is not appropriate, there is a problem in that the power transmission device starts power transmission and transmission efficiency decreases.

  The present invention has been made in view of the above problems, and an object of the present invention is to enable wireless power transmission based on the positional relationship between a power transmission device and a power reception device.

As a means for achieving the above object, a power transmission device of the present invention has the following configuration. That is, a power transmission device that transmits power to a power receiving device, intermittent power transmission means that intermittently performs wireless power transmission, and ID received by the power receiving device between the intermittent power transmission and the power received by the power receiving device. Therefore, a first power transmission method including detecting a load-modulated signal, and performing the power transmission by modulating power according to the predetermined ID so that the power receiving apparatus detects a predetermined ID. Selecting means for selecting any one of the second power transmission methods including, and operating according to the power transmission method selected by the selection means.
(Insert claim 1)

  ADVANTAGE OF THE INVENTION According to this invention, it can detect efficiently that the positional relationship of a power transmission apparatus and a power receiving apparatus is appropriate.

1 is a diagram illustrating a wireless power transmission system according to an embodiment. The figure which shows the power transmission part structure of the power transmission apparatus by 1st Embodiment. The figure which shows the power receiving part structure of the power receiving apparatus by 1st Embodiment. The timing chart of the wireless power transmission system in a 1st embodiment. The flowchart which shows operation | movement of the power transmission apparatus by 1st Embodiment. The flowchart which shows operation | movement of the power receiving apparatus by 1st Embodiment. The figure which shows the appropriate positional relationship of a power transmission apparatus and a power receiving apparatus. The figure which shows the power transmission part structure of the power transmission apparatus by 2nd Embodiment. The figure which shows the power receiving part structure of the power receiving apparatus by 2nd Embodiment. The timing chart of the wireless power transmission system in 2nd Embodiment. The flowchart which shows operation | movement of the power transmission apparatus by 2nd Embodiment. The flowchart which shows operation | movement of the power receiving apparatus by 2nd Embodiment. The flowchart which shows another operation | movement of the power receiving apparatus by 2nd Embodiment. The figure which shows the authentication sequence of the wireless power transmission system by 3rd Embodiment. The flowchart which shows operation | movement of the power transmission apparatus by 3rd Embodiment. The flowchart which shows operation | movement of the power transmission apparatus by 4th Embodiment.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the accompanying drawings. The configurations shown in the following embodiments are merely examples, and the present invention is not limited to the illustrated configurations.

[First Embodiment]
The present embodiment will be described with reference to the drawings. FIG. 1 is a diagram illustrating a wireless power transmission system according to the present embodiment. The wireless power system according to the present embodiment includes a power transmission device 20 and a power reception device 30. The power transmission device 20 and the power reception device 30 respectively include a communication unit 22 and a communication unit 32 that perform wireless communication using, for example, Bluetooth (registered trademark). The communication unit 22 and the communication unit 32 convert digital signals transmitted through the communication line 26 and the communication line 36, respectively, and perform wireless communication through the antenna 24 and the antenna 34, respectively. The power transmission unit 21 in the power transmission device 20 converts direct current or alternating current power input from the transmission line 25 into alternating current frequency power in the transmission band, and transmits the power via the antenna 23. The power receiving unit 31 in the power receiving device 30 converts AC power received via the antenna 33 into DC power or AC power having a desired frequency, and outputs the AC power to the power transmission line 35.

  When using power transmission using resonance or microwaves, the power transmission distance is long, so pairing the power transmission device and power reception device to transmit power to the desired device, and power transmission to other devices and objects It is necessary to prevent. In the present embodiment, the power receiving device 30 first searches for the power transmitting device 20 via the communication unit 32, and performs authentication between the communication unit 32 and the communication unit 22. Specifically, an ID is exchanged between the communication unit 32 of the power receiving device 30 and the communication unit 22 of the power transmission device 20 at the time of authentication.

  FIG. 2 is a block diagram illustrating an example of details of the internal configuration of the power transmission unit 21 of the power transmission device 20. The CPU 212 includes an initial power transmission unit 2121, a power transmission period extension unit 2122, a detection mode signal detection unit 2123, an ID match determination unit 2124, a power reception efficiency calculation unit 2125, a normal power transmission unit 2126, and a foreign object detection unit 2127. The description of the function of each part of the CPU 212 will be described later. The display unit 27 displays information input from each unit of the CPU 212. The constant power transmission unit 214 is a constant voltage source or the like, and the initial power transmission unit 2121 of the CPU 212 sets power necessary for power reception and power necessary for a power transmission initial sequence (hereinafter referred to as “initial sequence”). The initial power transmission unit 2121 may further transmit initial power by periodic intermittent power transmission. The switch 215 is used when the initial power is periodically intermittently transmitted during the initial sequence. The switch 215 may be used for transmitting simple data to the power receiving device 30 by ON / OFF. In FIG. 2, the switch 215 is disposed between the constant power transmission unit 214 and the AC conversion unit 216. However, since the output power only needs to be ON / OFF, the switch 215 is provided in front of the constant power transmission unit 214 or the AC conversion unit 216. May be placed after. Further, the output of AC power may be turned on / off by turning on / off a drive signal of a switching element (not shown) inside the AC converter 216 instead of the switch 215. The AC conversion unit 216 converts direct current or alternating current such as commercial power into a frequency for power transmission.

  The power reception impedance detection unit 213 detects load modulation performed by the power reception device 30 and impedance changes of the antenna 33 and other power reception units 31. The power reception impedance detection unit 213 generally detects power reception impedance by detecting reflection due to mismatch between the power transmission device 20 side impedance including the power transmission antenna 23 and the power reception device 30 side impedance. Generally, since the coupling efficiency between power transmission and reception changes when the positional relationship between the power transmission and reception devices changes, reflection due to mismatching changes even if the power reception impedance of the power reception device 30 does not change. However, when the load modulation in the power receiving device 30 is performed with a predetermined value such as a unique word, the power receiving impedance detection unit 213 can distinguish whether the power receiving impedance is changed or the position is changed. In addition, the power reception impedance detection unit 213 can detect that an object is placed in a predetermined range from the power transmission device 20 based on a change in impedance on the power transmission device 20 side including the power transmission antenna 23.

  The initial impedance storage unit 217 stores the initial impedance when there is nothing around the power transmission device 20. When the power receiving impedance detection unit 213 detects an impedance different from the initial impedance without receiving the load modulation from the power receiving device 30 during initial power transmission, the foreign object detection unit 2127 controls the switch 215 to stop the initial power transmission. To do. Then, the foreign object detection unit 2127 displays the foreign object detection on the display unit 27. The ID storage memory 211 stores an ID determined by device authentication by the communication unit 22. Also, the ID match determination unit 2124 checks whether the ID included in the detection mode signal detected by the detection mode signal detection unit 2123 matches the ID stored in the ID storage memory 211, and if it matches, the ID match notification I do.

  After transmitting the ID match notification, the power transmission device 20 performs intermittent power transmission for power reception efficiency calculation. When receiving the intermittent power transmission for calculating the power receiving efficiency, the power receiving apparatus 30 transmits the received power amount to the power transmitting apparatus 20 via load modulation or the communication unit 32. When the power reception efficiency calculation unit 2124 of the CPU 212 detects the power reception power amount of the power reception device 30 from the impedance detection unit 213 or the communication unit 22, the power reception efficiency is calculated by comparing with the transmission power. The power reception efficiency calculation unit 2124 determines that the power reception efficiency is lower than a predetermined threshold value. The display unit 27 displays that the power receiving efficiency is poor, and prompts the user to move the power receiving device 30 to an appropriate position. On the other hand, when the power reception efficiency exceeds the threshold, the normal power transmission unit 2125 starts normal power transmission.

  Even if the initial sequence power transmission is intermittent power transmission and power is transmitted to a foreign object, it is desirable to secure a heat dissipation period for the foreign object and suppress a steady temperature rise due to continuous power transmission. However, when the transmission power in the initial sequence is sufficiently small and the foreign object detection time in the initial sequence is sufficiently short, the power transmission in the initial sequence can be performed by continuous power transmission.

  FIG. 3 is a block diagram showing an example of the details of the internal configuration of the power receiving unit 31 of the power receiving device 30 of FIG. The CPU 312 includes a detection mode signal generation unit 3121, a power calculation unit 3122, and an ID match notification reception unit 3123. The description of the function of each part of the CPU 312 will be described later. The display unit 37 displays information input from each unit of the CPU 312. 314 in the power reception unit 31 is an AC power conversion unit, which includes a rectifier circuit, a constant voltage source, and the like. The impedance changing unit 313 adjusts the matching of the power receiving antenna 33 and further performs load modulation with the detection mode signal. The impedance changing unit 313 keeps the impedance when the circuit side is viewed from the power receiving antenna 33 as high impedance unless the authentication in the communication unit 32 is finished. The detection mode signal generation unit 3121 of the CPU 312 reads the ID from the ID storage memory 311 that stores the ID determined by the authentication by the communication unit 32, and generates a detection mode signal. The impedance changing unit 313 performs load modulation with the generated detection mode signal.

  Next, operations in the initial sequence of the power transmission device 20 and the power reception device 30 will be described with reference to FIG. FIG. 4 shows a timing chart of the power transmission device 20 and the power reception device 30. In FIG. 4, the vertical axis of the power transmission device 20 schematically shows the amount of power transmission, and the vertical axis of the power reception device 30 schematically shows the power reception impedance. In the following description, as shown in FIG. 7, it is assumed that the power receiving device 30 is approaching the power transmitting device 20 to receive power. FIG. 7 shows a communication range 701, a power transmission range 702, and a range 703 in which power transmission is possible with appropriate efficiency when the power receiving device 30 approaches the power transmission device 20.

  When the power receiving device 30 enters the communication range 701 of the power transmitting device 20 illustrated in FIG. 7, the power receiving device 30 enters device authentication with the power transmitting device 20. In the device authentication, an ID is exchanged between the power transmission device 20 and the power reception device 30. When the device authentication 400 is completed, the power transmission device 20 starts initial power transmission for ID detection at a constant period. In this embodiment, initial power is intermittently transmitted (T401 to T405). At this time, the initial power transmission unit 2121 of the CPU 212 supplies the minimum power value necessary for the initial sequence until normal power transmission (until ID detection within the band with the power receiving device and confirmation of power reception efficiency is completed) at constant power transmission. Set in section 214. Specifically, the initial power transmission unit 2121 sets the load modulation of the power receiving device 30 to power that can be detected by the power transmission device 20 within a range including the range 703 in which power can be transmitted with appropriate efficiency.

  The power receiving apparatus 30 repeatedly performs load modulation with the detection mode signal including the ID exchanged at the time of device authentication 400, which is “1,0,1,0,0,1,0,1” in the example of FIG. 4 (R401 to R406). ). When the power receiving device 30 is separated from the power receiving device 20 and is not within the power receivable range, even if the power receiving device 30 performs load modulation, the transmitted power is not consumed, and almost all the intermittent power transmission from T401 to T404 is performed. reflect. When the power receiving device 30 enters the power transmission range 702 shown in FIG. 7 as the power receiving device 30 approaches the power transmitting device 20, the power modulated by the load modulation of the power receiving device 30 starts to be transmitted like the intermittent power transmission T405. .

  When the power transmission device 20 performs intermittent power transmission when transmission power starts to be modulated by the ID, the power transmission period of the intermittent power transmission is extended to the start point of the next detection mode signal, which is the ID start point in FIG. In FIG. 4, the detection mode signal is composed of only the ID, but may include a start bit sequence, a stop bit sequence, and other information. In addition, in the figure, for the sake of simplicity, the detection mode signal is only ID, and the power transmission period is extended based on partial detection of the ID, but the power transmission period is extended based on partial detection of the detection mode signal. May be. After extending the power transmission period of intermittent power transmission to the start point of the next detection mode signal, the power transmission device 20 continues power transmission to the end point of the detection mode signal in order to acquire an ID. In FIG. 4, the power transmission device 20 continues to transmit power until it detects the ID of the next detection mode signal. Thereafter, the power transmission device 20 checks a match between the detected ID and the ID determined by the device authentication. If they match, the power transmission device 20 transmits an ID match notification T406. The ID match notification T406 may be transmitted from the communication unit 22 of the power transmission device 20 to the communication unit 32 of the power reception device 30, or by controlling the constant power transmission unit 214 and the switch 215, the transmitted power is transmitted as an ID match notification signal. You may modulate and transmit. After transmitting the ID match notification, the power transmission device 20 starts intermittent reception for detecting power reception efficiency (T407 to 409).

  The power receiving device 30 detects the ID match notification after the power from the power transmitting device 20 exceeds the predetermined value, and then receives the intermittent power, measures the received power every time the intermittent power is received, and modulates the load with that value. (R407-409). The power transmission device 20 detects the received power value from the load-modulated value, and compares the power transmitted by the own device with the received power to calculate the power reception efficiency. In the example of FIG. 4, it is determined that the power reception efficiency exceeds a predetermined threshold at the time of the third intermittent transmission T409, and the power reception device 30 enters the appropriate efficiency transmission range 703 shown in FIG. Switching. In FIG. 4, the power receiving device 30 performs load modulation with the amount of received power and transmits it, but it may transmit from the communication unit 32 to the communication unit 22 of the power transmission device 20.

  In FIG. 4, the power transmission device 20 starts intermittent power transmission for power reception efficiency measurement after the ID match notification T406, but the power reception efficiency measurement method is not limited to this. That is, the power receiving device 30 detects the amount of received power at the time of low impedance at the time of load modulation by the detection mode signal, that is, at the time of transmitting “0” of R406, and the amount of received power at the time of receiving the ID match notification T406. May be notified. The notification of the received power amount may be a method using load modulation during ID match notification or out-of-band communication using the communication unit 32. Further, another power transmission period may be provided after the ID match notification, and may be performed during that period. It is clear that intermittent power transmission for detecting power reception efficiency is not necessary if the received power at the time of modulation by the detection mode signal or at the time of ID coincidence notification exceeds a predetermined threshold.

  Next, the operation of the power transmission device 20 will be described with reference to FIGS. 2 and 5. FIG. 5 is an example of a flowchart from device authentication of the power transmission device 20 to normal power transmission. When power transmission / reception device authentication is completed (S501), the initial power transmission unit 2121 sets the transmission power of the constant power setting unit 214 to initial setting power (S502), and starts ID detection initial power transmission (S503). . In the case of intermittent power transmission, the initial power is intermittently transmitted using the switch 215. The power receiving impedance detection unit 213 constantly monitors the impedance during the power transmission period of intermittent power transmission, and detects a device whose load is modulated by the detection mode signal including the ID determined in the device authentication S501. Here, the initial impedance storage unit 217 stores in advance an initial impedance in a state where there is no foreign object such as a device or metal that can receive power of a frequency transmitted to the periphery by the power transmission device 20.

  When the power reception impedance detection unit 213 detects an impedance different from the initial impedance (Yes in S504), the foreign object detection unit 2127 determines the presence of the foreign object. Specifically, the foreign object detection unit 2127 determines that a foreign object has been detected when it detects an impedance that is modulated by the ID and has no possibility of load modulation (Yes in S505). Then, the power reception impedance detection unit 213 controls the switch 215 via the CPU 212 to stop power transmission (S516), and performs an error display indicating foreign object detection via the display unit 27 (S517). For example, if the power reception impedance detection unit 213 detects an impedance that is constant different from the initial impedance, there is a possibility that a metal or the like is in proximity, so the display unit 27 displays that there is a metal object and moves to the user Prompt. Similarly, when the power receiving impedance detection unit 213 detects a load modulated signal in a format different from that of the power receiving device 30, there is a power receiving device of a different model or a device communicating in the same band in the vicinity. This is displayed on the display unit 27 to prompt the user to move. Here, since the power transmission device 20 has stopped power transmission, after the user removes the foreign matter, an operation such as pressing a button (not shown) indicating the completion of the foreign matter removal work is detected (S518), and ID detection initial power is detected. Return to power transmission (S503). If the transmission power of the ID detection initial power transmission is sufficiently small or the foreign object detection time is sufficiently small and the possibility of failure due to heat generation or power reception of the foreign object is sufficiently small (No in S504, No in S505), You may return to the ID detection initial power transmission (S503) without the user's return operation.

  When the impedance detected by the power reception impedance detection unit 213 is the same as the initial impedance, and when the detection mode signal detection unit 2123 partially detects the detection mode signal (Yes in S504), when initial power is intermittently transmitted The process proceeds to S506. Then, the power transmission period extending unit 2122 extends the power transmission period of intermittent power transmission until the head portion of the next detection mode signal is detected (S506). When the initial power is continuously transmitted, the process of S506 is not necessary. Here, if the detection mode signal detection unit 2123 does not detect the head portion of the next detection mode signal during a certain period, it has detected load modulation of a power receiving device of another standard or the desired power receiving device 30 It may have gone away. In this case, the detection mode signal detection unit 2123 displays an error on the display unit 27 and prompts the user to respond (S519). Then, by returning to the initial power transmission for ID detection, it is confirmed that other standard devices are excluded or the desired power receiving device 30 is detected. When the detection mode signal detection unit 2123 detects the start of the detection mode signal (Yes in S507), when the initial power is intermittently controlled, the power transmission period extension unit 2122 further extends the power transmission period until the detection mode signal completion time (S508). Here, even when the head of the detection mode signal is detected from the beginning in S504, the power transmission period until the detection mode signal is completed can be extended because the head portion of the detection mode signal in S507 has already been detected.

  The ID match determination unit 2124 checks for a match between the ID determined by the device authentication and the ID detected by the detection mode signal (S509). If the ID is different (No in S509), there is a possibility that another power receiving device of the same standard that has been authenticated with another power transmitting device exists in the vicinity, so that is displayed on the display unit 27 and moved to the user (S519). Then, by returning to the initial power transmission for ID detection, the exclusion of another power receiving device of the same standard can be confirmed. If it is determined that the IDs match (Yes in S509), the ID match determination unit 2124 transmits an ID match notification (S510). The ID match determination unit 2124 may transmit this ID match notification from the communication unit 22 to the communication unit 32 of the power receiving device 30, or control the constant power transmission unit 214 and the switch 215 to match the transmitted power with the ID match. You may transmit by modulating with a notification signal. After transmitting the ID match notification, the initial power transmission unit 2121 starts intermittent power reception efficiency detection transmission (S511). When the power receiving device 30 receives intermittent power, the power receiving device 30 measures the received power each time and performs load modulation with the measured value. The power reception efficiency calculation unit 2125 detects the power reception power value from the load-modulated value (S512), and compares the power transmitted by the own device with the power reception power to calculate the power reception efficiency (S513). When the power reception efficiency is equal to or less than a predetermined threshold, the power reception efficiency calculation unit 2125 determines that the power reception device 30 is not in the appropriate efficiency transmission range 703 shown in FIG. Display a recommendation to move to a location (520). When the efficiency exceeds the threshold value, the power reception efficiency calculation unit 2125 determines that the efficiency is within the appropriate efficiency transmission range 703, and switches the process to normal power transmission by the normal power transmission unit 2126 (S515).

  Next, the operation of the power receiving device 30 will be described with reference to FIGS. 3 and 6. FIG. 6 is an example of a flowchart from device authentication of the power receiving device 30 to normal power transmission. The impedance changing unit 313 sets the impedance of the antenna 33 or a load (not shown) (power reception impedance) high until the device authentication (S602) with the power transmission device 20 is finished, and transmits the power transmission device of another standard or the same standard. The power from the unauthorized power transmission device is not received (S601). This avoids heat generation and failure of the power receiving device. After the device authentication (S602), the power receiving apparatus 30 performs load modulation with the detection mode signal including the ID exchanged by the device authentication (S603). This detection mode signal is generated by a detection mode signal generation unit 3121. Further, this load modulation may be performed by the impedance changing unit 313 in FIG. 3 or by changing the load of the AC power converting unit 314. Further, ON / OFF of an antenna switch (not shown) may be used.

  When the power receiving device 30 is far from the power transmitting device 20, the power receiving device 30 receives little power (No in S604), but when the power receiving device 30 approaches the power transmitting device 20 and enters the power transmission range 702 in FIG. The electric power transmitted by the device 20 is modulated by the load modulation of the own device and received (Yes in S604). That is, it becomes a power detection state. If the power transmitting device is a device that has been authenticated by device authentication (S602), an ID match notification is transmitted from the power transmitting device 20 following the completion of load modulation of the detection mode signal by the power receiving device 30 (S603, S604). Yes). For this reason, the impedance changing unit 313 sets the power receiving impedance to such an extent that the ID match notification can be received after the completion of the next detection mode signal modulation after the power detection (S605). However, the ID match notification may be performed via the communication units 22 and 23. In FIG. 6, the modulation by the detection mode signal is stopped after the power detection, but the detection mode signal modulation may be continued until the ID match notification is received. Further, when the ID match notification is transmitted / received via the communication units 22 and 32, the impedance changing unit 313 may set the power receiving impedance high after the detection mode signal modulation is completed.

  If the ID match notification is not received even if power is detected (No in S606), there is a possibility of power transmission from another standard power transmission device or power reception from another power transmission device of the same model. An error is displayed in 37 (S611), and the user is prompted to move the position. When the power receiving device 30 receives the ID match notification (Yes in S606), the impedance changing unit 313 sets the power receiving impedance low (S607), and receives the intermittent power transmission for calculating the power receiving efficiency. Each time the power receiving device 30 receives power, the power receiving device 30 returns the received power by load modulation, or returns information on the received power via the communication units 32 and 22 (S608). However, each time the power receiving device 30 receives power, it simply returns the received power by load modulation or via the communication units 32 and 22 (S611), and this process is continued until it is determined that the power is continuously received (No in S609). ). If it is determined that power is continuously received (Yes in S609), it is determined that power is normally received (S610).

  As described above, the power transmission device 20 according to the present embodiment does not start power transmission unless the desired power transmission target for which authentication has been performed enters a range in which the desired power can be supplied and the power transmission target does not match the desired power transmission target. Thereby, although it is not a power transmission object, the heat_generation | fever and the failure by electric power transmission can be prevented. In addition, the power receiving device 30 according to the present embodiment reduces the power receiving impedance only when power from the authenticated power transmitting device is supplied, thereby preventing unnecessary power reception from an unauthenticated device and damaging the device. The possibility of this can be reduced.

  In the present embodiment, the power transmission device 20 starts normal power transmission when the power receiving efficiency is equal to or higher than the threshold after determining the ID match, but may start normal power transmission after determining the ID match. . In addition, the power transmission device 20 determines an appropriate positional relationship with the power receiving device 30 from the power receiving efficiency that can be calculated from the power received by the power receiving device 30, but from the power received by the power receiving device 30 even if it is other than the power receiving efficiency. Any value can be used. In this embodiment, intermittent power transmission is performed from the power transmission device in order to calculate power reception efficiency. However, a step of calculating power reception efficiency by continuous power transmission may be performed.

[Second Embodiment]
The present embodiment will be described with reference to the drawings. Since the wireless power transmission system according to the present embodiment is the same as that of FIG. 1 described in the first embodiment, description thereof is omitted. The power transmission device 20 according to the present embodiment differs from the first embodiment in the configurations of the power transmission unit 21 and the power reception unit 31.

  FIG. 8 is a block diagram illustrating an example of details of the internal configuration of the power transmission unit 21 of the power transmission device 20. The CPU 812 includes an initial power transmission unit 8121, a detection mode signal generation unit 8122, an ID match notification reception unit 8123, a power reception efficiency calculation unit 8124, a normal power transmission unit 8125, and a foreign object detection unit 8126. The description of the function of each part of the CPU 812 will be described later. The display unit 27 displays information input from each unit of the CPU 812. The constant power transmission unit 814 is a constant voltage source or the like, and the power necessary for power reception and the power necessary for the initial transmission sequence (hereinafter referred to as “initial sequence”) are set by the initial power transmission unit 8121 of the CPU 812. The initial power transmission unit 8121 may further transmit initial power by periodic intermittent power transmission. The power transmission device 20 can perform simple data transmission to the power reception device 30 by modulating the output of the constant power transmission unit 814.

  The switch 815 is used when the initial power is periodically intermittently transmitted during the initial sequence. The switch 815 may be used for transmitting simple data to the power receiving device 30 by ON / OFF. The AC converter 816 converts direct current or alternating current such as commercial power into a frequency for power transmission. In FIG. 2, the switch 815 is disposed between the constant power transmission unit 814 and the AC conversion unit 816. However, since it is sufficient that the output power can be turned ON / OFF, the switch 815 is provided in front of the constant power transmission unit 814 or AC conversion. It may be arranged after the part 816. Further, instead of the switch 815, the output of AC power may be turned ON / OFF by turning ON / OFF the drive signal of a switching element (not shown) inside the AC converter 816. The AC converter 816 converts direct current or alternating current such as commercial power into a frequency for power transmission.

  The power reception impedance detection unit 813 detects load modulation performed by the power reception device 30 and impedance changes of the antenna 33 and other power reception units 31. The power reception impedance detection unit 813 generally detects power reception impedance by detecting reflection due to mismatch between the power transmission device 20 side impedance including the power transmission antenna 23 and the power reception device 30 side impedance. Generally, since the coupling efficiency between power transmission and reception changes when the positional relationship between the power transmission and reception devices changes, reflection due to mismatching changes even if the power reception impedance of the power reception device 30 does not change. However, when the power receiving device 30 returns a signal indicating power reception or the like by load modulation, the power receiving impedance detection unit 813 can distinguish whether the power receiving impedance changes or the position changes.

  The initial impedance storage unit 817 stores an initial impedance when there is nothing around the power transmission device 20. When the power receiving impedance detection unit 813 detects an impedance different from the initial impedance without receiving load modulation from the power receiving device 30 during initial power transmission, the foreign object detection unit 8126 controls the switch 815 to stop the initial power transmission. To do. Then, the foreign object detection unit 8126 performs an error display indicating the detection of the foreign object via the display unit 27. The ID storage memory 811 stores an ID determined by device authentication by the communication unit 22. The detection mode signal generation unit 8122 generates a detection mode signal based on the ID stored in the ID storage memory 811. The output of the constant power transmission unit 814 is modulated by the generated detection mode signal and transmitted. Note that the power modulated by the detection mode signal may be transmitted using ON / OFF of the switch 815.

  The power receiving device 30 that has performed device authentication receives the power transmission modulated by the detection mode signal, and transmits an ID match notification when the ID match is confirmed. The power transmission device 20 receives the ID match notification via load modulation of transmission power or the communication unit 22. When the ID match notification receiving unit 8123 receives the ID match notification, the power transmitting device 20 can recognize that the power receiving device 30 has entered the power receivable range from the power transmitting device 20.

  After receiving the ID match notification, the power transmission device 20 performs intermittent power transmission for power reception efficiency calculation. When receiving the intermittent power transmission for calculating the power receiving efficiency, the power receiving apparatus 30 transmits the received power amount to the power transmitting apparatus 20 via load modulation or the communication unit 32. When the power reception efficiency calculation unit 8124 of the CPU 812 detects the power reception power amount of the power reception device 30 from the impedance detection unit 813 or the communication unit 22, the power reception efficiency calculation unit 8124 calculates the power reception efficiency compared with the transmission power. When the power reception efficiency is lower than a predetermined threshold, the power reception efficiency calculation unit 8124 is. The display unit 27 displays that the power receiving efficiency is poor, and prompts the user to move the power receiving device 30 to an appropriate position. On the other hand, when the power reception efficiency exceeds the threshold value, the normal power transmission unit 8125 starts normal power transmission. Even if the initial sequence power transmission is intermittent power transmission and power is transmitted to a foreign object, it is desirable to secure a heat dissipation period for the foreign object and suppress a steady temperature rise due to continuous power transmission. For example, power transmission modulated in the detection mode signal period and power transmission with a period of a heat dissipation period of a foreign object as one cycle. However, if the initial sequence transmission power is sufficiently small and the foreign object detection time in the initial sequence is sufficiently short, if the detection mode signal includes a signal indicating the start bit, stop bit, etc., the initial sequence transmission is continuously transmitted. It is also possible to do this.

  FIG. 9 is a block diagram showing an example of the details of the internal configuration of the power receiving unit 31 of the power receiving device 30 of FIG. The CPU 912 includes a detection mode signal determination unit 9121, a power calculation unit 9122, and an ID match notification generation unit 9123. A description of the function of each part of the CPU 912 will be described later. The display unit 37 displays information input from each unit of the CPU 912. The AC power conversion unit 914 includes a rectifier circuit, a constant voltage source, and the like. The impedance changing unit 913 adjusts the matching of the power receiving antenna 33 and further performs load modulation when it is desired to transmit data to the power transmitting device in the power transmitting / receiving frequency band. The impedance changing unit 913 sets the impedance when the circuit side is viewed from the power receiving antenna 33 to a high value unless authentication by the wireless unit 32 is completed. When the authentication in the wireless unit 32 is completed, the power receiving impedance is lowered.

  The ID storage memory 911 stores the ID determined by the authentication by the communication unit 32. When the communication unit 32 detects a power signal from the power transmission device 20, the detection mode signal determination unit 9121 determines whether the signal is a detection mode signal. When the ID included in the detection mode signal matches the ID stored in the ID storage memory 911, the ID match notification generation unit 9123 generates an ID match notification and transmits the ID match notification to the power transmission device 20. Furthermore, the power calculation unit 9122 calculates the received power amount detected by the AC power conversion unit 914, and transmits the received power amount to the power transmission device 20 via the load modulation or communication unit 32.

  Next, operations in the initial sequence of the power transmission device 20 and the power reception device 30 will be described with reference to FIG. FIG. 10 shows a timing chart of the power transmission device 20 and the power reception device 30. In FIG. 10, the vertical axis of the power transmission device 20 schematically shows the amount of power transmission, and the vertical axis of the power reception device 30 schematically shows the amount of power reception. Further, ZR01 to ZR03 of the power receiving device 30 indicate that the power receiving impedance is set to a high value. In the following description, as shown in FIG. 7, it is assumed that the power receiving device 30 is approaching the power transmitting device 20 to receive power. FIG. 7 shows a communication range 701, a power transmission range 702, and a range 703 in which power transmission is possible with appropriate efficiency when the power receiving device 30 approaches the power transmission device 20.

  When the power receiving device 30 enters the communication range 701 of the power transmitting device 20 illustrated in FIG. 7, the power receiving device 30 enters device authentication with the power transmitting device 20. In the device authentication, an ID is exchanged between the power transmission device 20 and the power reception device 30. When the device authentication 1000 is completed, the power transmission device 20 starts initial power transmission of power modulated by the detection mode signal at a constant period (T1001 to T1007). In the example of FIG. 10, the power transmission device 20 periodically transmits the power modulated by the detection mode signal including the exchanged ID “1,0,1,0,0,1,0,1”. . At this time, the initial power transmission unit 8121 of the CPU 812 supplies the minimum power value necessary for the initial sequence until normal power transmission (until ID detection within the band with the power receiving device and confirmation of power reception efficiency) at constant power transmission. Part 814. Specifically, the initial power transmission unit 8121 sets the power modulated by the detection mode signal of the power transmission device 20 to the power that can be received by the power reception device 30 within a range including the range 703 in which power transmission can be performed with appropriate efficiency. To do. The initial power transmission unit 8121 may intermittently transmit the initial power modulated by the detection mode signal as shown in FIG.

  The power receiving device 30 increases the power receiving impedance until the end of the device authentication 1000 (ZR01). After the device authentication, the power receiving device 30 is changed to low impedance, and the detection mode signal including the ID determined by the device authentication, “1,0,1,0,0,1,0,1” in the example of FIG. Wait for modulated power transmission. When the power receiving device 30 is separated and not within a range where power can be received, the transmitted power is not consumed even if the power receiving device 30 stands by at low impedance, and intermittent power transmission from T1001 to T1004 is almost Total reflection. When the power receiving device 30 enters the power transmission range 702 shown in FIG. 7 while the power receiving device 30 approaches the power transmitting device 20, power transmission to the power receiving device 30 starts like intermittent power transmission T1005.

  The power receiving device 30 waits for power transmission with low impedance after the device authentication in the communication unit 32. When the power receiving device 30 receives power transmission that is not modulated with the detection mode signal like R1001, the power receiving impedance is increased like ZR02, and the power receiving device avoids failure or heat generation due to power feeding from other devices. To do. Furthermore, the power receiving device 30 displays that the power is supplied from another device via the display unit 37, and prompts the user to keep the power receiving device 30 away from the other power transmitting device. Then, the power receiving device 30 lowers the power receiving impedance again after detecting the user's return operation, for example, an action such as pressing a button (not shown). Here, if the amount of power received from other devices does not generate heat more than allowable and does not affect the circuit failure of the power receiving device 30, the power receiving device 30 does not need to increase the power receiving impedance, and the user must perform a return work. Absent.

  When receiving power R1006 modulated by the detection mode signal after receiving a part R1005 of the ID included in the detection mode signal, the power receiving device 30 is included in the detection mode signal from the change pattern of the amount of power received by the power R1006. Detect ID. And then. The power receiving device 30 determines whether or not the detected ID matches the ID determined at the time of device authentication. When the IDs match, the power receiving device 30 transmits an ID match notification R1007 to the power transmitting device 20. Note that FIG. 10 shows an example in which the power R1007 received in correspondence with the transmitted power T1007 is load-modulated by changing the power receiving impedance like ZR03, and the ID matching notification is sent to the power transmitting device 20. However, it may be notified that the ID has been detected via the communication unit 32. In FIG. 10, the detection mode signal is composed of only the ID, but may include a start bit, a stop bit, and other information.

  After detecting the ID match notification, the power transmission device 20 starts intermittent power reception efficiency detection transmission (T1008 to 1010). After receiving the ID match notification, the power receiving device 30 receives the intermittent power from the power transmitting device 20, and measures the received power each time and performs load modulation with the value (R1008 to 1010). The power transmission device 20 detects the received power value from the load-modulated value, and compares the power transmitted by the own device with the received power to calculate the power reception efficiency. In the example of FIG. 10, the power reception efficiency exceeds a predetermined threshold at the time of the third intermittent transmission T1010, and it is determined that the power reception device 30 has entered the appropriate efficiency transmission range 703 shown in FIG. Switching. In FIG. 10, the power receiving device 30 transmits the received power amount by load modulation, but may be transmitted from the communication unit 32 to the communication unit 22 of the power transmission device 20.

  In FIG. 10, the power transmission device 20 starts intermittent power transmission for power reception efficiency measurement after receiving the ID match notification T1007, but the power reception efficiency measurement method is not limited to this. That is, the power receiving apparatus 30 may detect the received power amount when receiving the ID match notifications T1006 and T1007, that is, the received power amount of R1006 and R1007, and notify the power transmitting apparatus 20 of the detected power amount. As this notification, there can be considered a method of the received power amount notification by load modulation during the ID match notification and out-of-band communication using the communication unit 32. It is clear that intermittent power transmission for detecting power reception efficiency is not necessary if the received power at the time of modulation by the detection mode signal or at the time of ID coincidence notification detection exceeds a predetermined threshold.

  Next, the operation of the power transmission device 20 will be described with reference to FIGS. 8 and 11. FIG. 11 is an example of a flowchart from device authentication of the power transmission device 20 to normal power transmission. When the power transmission / reception device authentication is completed (S1101), the initial power transmission unit 8121 sets the transmission power of the constant power transmission unit 814 to the initial setting power (S1102), and starts the initial power transmission modulated by the detection mode signal. (S1103). In the case of intermittent power transmission, the initial power modulated in the detection mode may be intermittently transmitted using the switch 815. The power reception impedance detection unit 813 constantly monitors the impedance during the power transmission period of the initial power transmission, and detects a device whose load is modulated by the detection mode signal including the ID determined in the device authentication S1101. Here, the initial impedance storage unit 817 stores in advance an initial impedance in a state where there is no foreign object such as a device or metal that can receive power of a frequency transmitted to the periphery by the power transmission device 20.

  When the power reception impedance detection unit 813 detects an impedance different from the initial impedance (Yes in S1104), the power transmission device 20 waits for the detection mode signal transmission period or longer while continuing the initial power transmission (S1105). If the ID match notification receiving unit 8123 does not receive the ID match notification from the power receiving device 30 (No in S1106), power transmission is stopped by controlling the switch 815 (S1107), and the display unit 27 is used. Display indicating foreign object detection (S1108). For example, when an impedance that is constant different from the initial impedance is detected, there is a possibility that a metal or the like is close, so that there is a metal object and the user is prompted to move. Similarly, when the power receiving impedance detection unit 813 detects a load modulated signal in a format different from the response of the power receiving device 30, a power receiving device of a different model or a device that performs communication in the same band is in the vicinity. Since it exists, the fact is displayed and the user is prompted to move. Here, since the power transmission device 20 has stopped power transmission, after the user removes the foreign matter, an operation such as pressing a button (not shown) indicating the completion of the foreign matter removal operation is detected (S1109), and modulated by the detection mode signal. Return to the initial power transmission performed (S1103). If the transmission power of the initial power transmission is sufficiently small, or if the foreign object detection time is sufficiently small and the possibility of failure due to heat generation or power reception is sufficiently small, the power transmission is not stopped and the initial operation is not performed without user's return work. You may return to electric power transmission (S1103).

  When the ID match notification receiving unit 8123 receives the ID match notification after the power receiving impedance detection unit 813 detects the impedance change (Yes in S1106), the initial power transmission unit 8121 starts intermittent power transmission for calculating received power (S1111). Here, normally, when the power receiving device 30 receives power modulated by the detection mode signal, the power transmitting device 20 detects a change in impedance. However, when the signal detection sensitivity of the power receiving device 30 is higher than the sensitivity of detecting the impedance change of the power transmitting device 20, the power transmitting device 20 may detect the ID match notification of the power receiving device even if the impedance change cannot be detected. As described above, even when the power reception impedance detection unit 813 does not detect the impedance change (No in S1104) and the ID match notification reception unit 8123 detects the ID match notification (S1110), the power transmission apparatus performs intermittent power transmission for calculating received power (S1110). S1111) is started. When the power reception impedance detection unit 813 does not detect the impedance change and the ID match notification reception unit does not detect the ID match notification, the initial power transmission unit 8121 continues the initial power transmission modulated by the detection mode signal (S1104). No, S1110 No).

  When receiving the intermittent power for calculating received power, the power receiving device 30 measures the received power each time and performs load modulation with the measured value. The power reception efficiency calculation unit 8124 detects the power reception power value from the load-modulated value (S1112), and calculates the power reception efficiency by comparing the power transmitted by the own apparatus with the power reception by the comparison unit (not shown) in the CPU 812. (S1113). When the power reception efficiency is equal to or lower than a predetermined threshold, the power reception efficiency calculation unit 8124 determines that the power reception device 30 is not in the appropriate efficiency transmission range 703 shown in FIG. A recommendation for moving to a position is displayed (S1115). If the efficiency exceeds the threshold value, the power reception efficiency calculation unit 8124 determines that the efficiency is within the appropriate efficiency transmission range 703, and switches the process to normal power transmission by the normal power transmission unit 8125 (S1116).

  Next, the operation of the power receiving device 30 will be described with reference to FIGS. 9 and 12. FIG. 12A is an example of a flowchart from device authentication of the power receiving device 30 to normal power transmission. The impedance changing unit 913 sets the impedance of the antenna 33 or a load (not shown) (power reception impedance) high until the device authentication (S1202) with the power transmission device 20 is finished, and transmits the power transmission device of another standard or the same standard. The power from the power transmission device that is not authenticated is not received (S1201). This avoids heat generation and failure of the power receiving device. After the device authentication in the communication unit 32, the impedance changing unit 913 changes the power receiving impedance to a low level (S1203) and waits until power is detected (No in S1204).

  When the power reception unit 31 detects power (Yes in S1204), the detection mode signal determination unit 9121 determines whether or not the received power is modulated with a detection mode signal including an ID determined at the time of authentication. The detection mode signal determination unit 9121 determines whether or not the received power is modulated with a detection mode signal including an ID determined at the time of authentication. That is, the detection mode signal determination unit acquires an ID from the received power, and determines whether the acquired ID matches the ID stored in the ID storage unit 911. When the detection mode signal determining unit determines that the IDs do not match (No in S1205), the impedance changing unit 913 increases the power receiving impedance (S1206). Thereby, it is avoided that the power receiving device 30 breaks down due to power supply from other devices or generates heat. Further, the detection mode signal determination unit 9121 displays that power is supplied from another device on the display unit 37 (S1207), and prompts the user to keep the power receiving device 30 away from the other power transmission device. Then, the power receiving device 30 detects a user's return operation, for example, an action such as pressing a button (not shown) (S1208), and the impedance changing unit 913 lowers the power receiving impedance again (S1209). Here, if the amount of power received from another device does not generate heat more than allowable and does not affect the circuit failure of the power receiving device 30, a change is made to increase the power receiving impedance of 606, and the completion of user return work completion in S1208 is also detected. unnecessary. Furthermore, since the power receiving impedance is not preceded, the work of changing to the low impedance of S1209 is not necessary.

  On the other hand, when the power reception unit 31 detects power (Yes in S1204) and the detection mode signal determination unit determines that the IDs do not match (Yes in S1205), the ID match notification generation unit 9123 generates an ID match notification And transmitted to the power transmission device 20 (S1210). The ID match notification may be transmitted using load modulation or via the communication unit 32. The power receiving device 30 receives the intermittent power transmission for calculating the power receiving efficiency after transmitting the ID match notification. However, every time the power receiving device 30 receives power, the power receiving device 30 simply returns the received power by load modulation or via the communication units 32 and 22 (S1211). Continue until continuous power reception is determined (No in S1212). If it is determined that power is continuously received (Yes in S1212), it is determined that power is normally received (S1213).

  FIG. 12B is a flowchart illustrating another impedance setting procedure of the power receiving device 30. After the device authentication (S1202), the impedance changing unit 913 sets the power reception impedance to an intermediate value (S1214). On the other hand, if the IDs do not match (No in S1205), the impedance changing unit 913 sets the power receiving impedance to an intermediate value after the power return impedance is increased, and after the return operation by the user (S1215). The impedance changing unit 913 changes to a low power receiving impedance for normal power reception for the first time after transmitting the ID match notification (S1216). As a result, the power receiving device 30 does not have a low impedance unless the ID is confirmed within the power transmission band, so that a failure due to heat generation or power reception can be reduced. Note that the order of the processing in S2110 and S1216 may be reversed.

  As described above, the power transmission device 20 according to the present embodiment does not start predetermined power transmission unless the desired power transmission target that has been authenticated enters a position where desired power can be supplied and the power transmission target does not match the desired power transmission target. Thereby, although it is not a power transmission object, the heat_generation | fever and the failure by electric power transmission can be prevented. In addition, when power is supplied from a power transmission device that has not been authenticated, the power receiving device 30 according to the present embodiment detects and displays it. Furthermore, when power is supplied from a power transmission device that has not been authenticated, the power receiving device 30 can increase power reception impedance and prevent power reception, thereby preventing unnecessary power reception from a device that has not been authenticated, The possibility of equipment damage can be reduced.

  In the present embodiment, after detecting the ID match notification, the power transmission device 20 starts normal power transmission when the power receiving efficiency is equal to or higher than the threshold. However, after detecting the ID match notification, the power transmission device 20 starts normal power transmission. Also good. In addition, the power transmission device 20 determines an appropriate positional relationship with the power receiving device 30 from the power receiving efficiency that can be calculated from the power received by the power receiving device 30, but the power received by the power receiving device 30 is not limited to the power receiving efficiency. Any relevant value is acceptable. In this embodiment, intermittent power transmission is performed from the power transmission device in order to calculate power reception efficiency. However, a step of calculating power reception efficiency by continuous power transmission may be performed.

[Third Embodiment]
The present embodiment will be described with reference to the drawings. Since the wireless power transmission system according to the present embodiment is the same as that of FIG. 1 described in the first embodiment, description thereof is omitted. The power transmission device 20 according to the present embodiment is different in the configurations of the power transmission unit 21 and the power reception unit 31 compared to the first embodiment and the second embodiment.

  If the operation of the power transmission device 20 in the first embodiment is the first power transmission method and the operation of the power transmission device 20 in the second embodiment is the second power transmission method, the power transmission device 20 according to the present embodiment It is possible to operate by switching. That is, the internal configuration of the power transmission device 20 according to the present embodiment is a configuration combining the configurations shown in FIG. 2 and FIG. However, the power transmission device 20 according to the present embodiment includes a selection unit (not illustrated) that performs control for operating in either the first power transmission method or the second power transmission method. On the other hand, when the operation of the power receiving device 30 in the first embodiment is the first power receiving method and the operation of the power receiving device 30 in the second embodiment is the second power receiving method, the power receiving device 30 according to the present embodiment is either It can be operated in a manner. That is, the internal configuration of the power receiving device 30 according to the present embodiment is the configuration shown in FIG. 3 or FIG.

  Next, the operation of the power transmission device 20 will be described with reference to FIGS. 13 and 14. FIG. 13 is a diagram illustrating an authentication sequence between the power transmission device 20 and the power reception device 30. FIG. 14 is a flowchart showing the operation according to the present embodiment. When the power transmission device 20 starts power transmission, first, authentication with the power reception device 30 is performed. The power transmission device 20 transmits a connection enable notification from the communication unit 22 (1301). The power receiving apparatus 30 within the range of the communication range 701 receives the connection permission notification, and issues a connection request at the communication unit 32 (1302). The power transmitting device 20 transmits a connection permission to the power receiving device 30 (1303). Thereby, a radio link is established (S1401). Next, the power transmitting apparatus 20 transmits the ID (1304), and the power receiving apparatus 30 returns a response indicating that the ID has been received (1305). Thereby, the ID is determined (S1402). This is the device authentication process.

  Furthermore, the power transmission device 20 requests the power reception method of the power reception device 30 (1306). The power receiving device 30 responds to the power transmitting device 20 as to whether the power receiving method provided is the first power receiving method or the second power receiving method (1307, S1403). When the power receiving apparatus operates in the first power receiving method, the power receiving device responds to that effect (first power receiving method in S1404). In response to this result, the power transmitting device 20 transmits a power transmission start notification (1308), and the power receiving device 30 returns a response (1309) to start power transmission in the first power transmission method (1310, S1406). Since the operation content of power transmission in the first power transmission method is the same as that of the first embodiment, description thereof is omitted. Note that the power transmission start notification and response are not necessarily indispensable sequences. When the response indicating that the operation is performed in the second power receiving method in the power receiving method response (1307) (second power receiving method in S1404), the power transmission device 20 starts power transmission in the second power transmission method (S1405). Since the operation content of power transmission in the second power transmission method is the same as that of the second embodiment, description thereof is omitted.

  As described above, the power transmission device 20 according to the present embodiment switches and executes the processing according to the power transmission method described in the first embodiment and the second embodiment according to the response of the power reception device 30. Thereby, although it is not a power transmission target, heat generation and failure due to power transmission can be prevented, and power can be received by a plurality of power receiving apparatuses having different power receiving methods. In addition, the power receiving device 30 according to the present embodiment can prevent unnecessary power reception from an unauthenticated device and reduce the possibility of damage to the device, in addition to a power transmission method corresponding to its own power receiving method and the others. It is also possible to receive power from a power transmission device that operates in both power transmission methods. In the above description, the power transmission device 20 requests the power reception device 30 for a power reception method, and the power reception method is determined according to the response content. However, when there is no response to the request for the power reception method from the power transmission device 20, it may be determined in advance which charging method is to be selected, and the power reception method may be selected. For example, when a response to the power reception method request from the power transmission device 20 to the power reception device 30 is not performed, “method 1” is determined between the power transmission device 20 and the power reception device 30. In this case, if the power receiving method of the power receiving apparatus 30 that has received the request for the power receiving method in the authentication sequence is “method 1”, no response is returned. Since the power transmission device 30 does not respond to the request for the power reception method, the power transmission device 30 performs power transmission according to method 1. Since the power receiving device 30 desires to receive power, it often does not want to use much power. This method can contribute to the reduction of wasted power. The same applies to the case where method 2 does not respond to a request for a power receiving method. The method for determining the method when the power receiving device does not respond 30 selects the widely used method, and the power reduction effect of the power receiving device 30 is enhanced.

[Fourth Embodiment]
The present embodiment will be described with reference to the drawings. Since the wireless power transmission system according to the present embodiment is the same as that of FIG. 1 described in the first embodiment, description thereof is omitted. The power transmission device 20 according to the present embodiment is different in the configurations of the power transmission unit 21 and the power reception unit 31 compared to the first embodiment and the second embodiment. Further, similarly to the power transmission device 20 and the power reception device 30 according to the third embodiment, the power transmission device 20 according to the present embodiment can be operated by switching between the first power transmission method and the second power transmission method. That is, the internal configuration of the power transmission device 20 according to the present embodiment is a configuration combining the configurations shown in FIG. 2 and FIG. However, the power transmission device 20 according to the present embodiment includes a selection unit (not illustrated) that performs control for operating in either the first power transmission method or the second power transmission method. In addition, the power receiving device according to the present embodiment can be operated in any one of the first power receiving method and the second power receiving method. That is, the internal configuration of the power receiving device 30 according to the present embodiment is the configuration shown in FIG. 3 or FIG.

  Next, the operation of the power transmission device 20 will be described with reference to FIG. FIG. 15 is a flowchart showing the operation according to the present embodiment. The power transmission device 20 establishes a wireless link with the power reception device 30 (S1501), and determines an ID (S1502). Up to this point, the power transmission device 20 does not know the power reception method (the first power reception method or the second power reception method) provided in the power reception device 30. The power transmission device 20 starts a power transmission procedure in the second power transmission method using the ID determined in the authentication sequence (S1503). At this time, when the power receiving apparatus can operate in the second power receiving system, the operation is the same as that described in the second embodiment, and the power receiving apparatus 30 can receive power (S1505).

  On the other hand, when the power receiving apparatus 30 operates in the first power receiving method, the power receiving 30 apparatus similarly changes the impedance according to the ID with respect to the power transmitted according to the predetermined ID. Will greatly disturb the transmitted power. In such an operation, the power transmission device 20 determines that the power reception device 30 operates in the first power reception method, and the power transmission device 20 performs intermittent power transmission for ID detection in the first power transmission method, which has been described in the first embodiment. The operation proceeds to the power transmission operation similar to the operation (S1506). When the power transmission device 20 first performs the power transmission procedure of the first power transmission method, when the power reception device 30 operates in the second power reception method, IDs are not transmitted to each other, so that the power transmission procedure does not proceed.

  As described above, the power transmission device 20 according to the present embodiment switches and executes the processing according to the power transmission method described in the first embodiment and the second embodiment based on its own judgment. Thereby, although it is not a power transmission target, heat generation and failure due to power transmission can be prevented, and power can be received by a plurality of power receiving apparatuses having different power receiving methods. In addition, the power receiving device 30 according to the present embodiment can prevent unnecessary power reception from an unauthenticated device and reduce the possibility of damage to the device, in addition to a power transmission method corresponding to its own power receiving method and the others. It is also possible to receive power from a power transmission device that operates in both power transmission methods.

[Other Embodiments]
The present invention can also be realized by executing the following processing. That is, software (program) for realizing the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, etc.) of the system or apparatus reads the program. It is a process to be executed.

Claims (10)

A power transmission device for transmitting power to a power receiving device,
Intermittent power transmission means for performing wireless power transmission intermittently;
During the intermittent power transmission, the power receiving device detects a first power transmission method including detecting a signal subjected to load modulation according to an ID by the power receiving device with respect to the transmitted power, and a predetermined ID. And selecting means for selecting one of the second power transmission methods including performing the power transmission by modulating the power according to the predetermined ID as described above,
A power transmission device that operates according to the power transmission method selected by the selection means.   The power transmission device according to claim 1, wherein the selection unit selects either the first power transmission method or the second power transmission method based on a response to a request to the power receiving device.   The selection means selects either the first power transmission method or the second power transmission method based on a change in impedance when operated according to the second power transmission method. The power transmission device according to 1.   When the load-modulated signal is detected, the first power transmission method includes extending a power transmission period by the intermittent power transmission means until an ID is acquired from the load-modulated signal. The power transmission device according to any one of claims 1 to 3.   5. The power transmission according to claim 4, wherein the first power transmission method starts normal power transmission when it is determined that the ID acquired by extending the power transmission period matches the predetermined ID. 6. apparatus.   The power transmission apparatus according to claim 5, wherein the first power transmission method starts the normal power transmission when a value related to received power of the power receiving apparatus is equal to or greater than a threshold value.   The second power transmission method according to any one of claims 1 to 3, wherein in the intermittent power transmission, normal power transmission is started when a notification that the power receiving device has detected the predetermined ID is detected. The power transmission device according to any one of claims.   The power transmission device according to claim 7, wherein the second power transmission method starts the normal power transmission when a value related to the received power of the power reception device is equal to or greater than a threshold value. A method of controlling a power transmission device that transmits power to a power receiving device,
An intermittent power transmission process for intermittently transmitting power by wireless;
During the intermittent power transmission, the power receiving device detects a first power transmission method including detecting a signal subjected to load modulation according to an ID by the power receiving device with respect to the transmitted power, and a predetermined ID. And selecting a second power transmission method including performing power transmission by modulating power according to the predetermined ID as described above,
A method for controlling a power transmission device, which operates according to the power transmission method selected in the selection step.   The program for making a computer perform each process of the control method of the power transmission apparatus described in Claim 9.

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