Power transmitting apparatus, power transmitting method, and storage medium

A power transmitting apparatus, which simultaneously or sequentially supplies electric power to a plurality of power receiving apparatuses in a wireless manner, includes a power transmitting unit configured to transmit electric power to the plurality of power receiving apparatuses, a reception unit configured to receive a power transmission end request and an abnormality content regarding power transmission from a first power receiving apparatus from among the plurality of power receiving apparatuses, and a power transmission determination unit configured, based on the abnormality content, to determine whether to stop power transmission to power receiving apparatuses that have not completed power transmission and that are not the first power receiving apparatus from among the plurality of power receiving apparatuses.

BACKGROUND

Field

Aspects of the present invention generally relate to a power transmitting apparatus, a power transmitting method, and a storage medium.

Description of the Related Art

Conventionally, there has been provided a technique for supplying electric power in a non-contact manner (a wireless manner). There are four types of non-contact power supply methods, that is, an electromagnetic induction method, a magnetic field resonance method, an electric field coupling method, and a radio wave receiving method. Among these methods, the magnetic field resonance method can transmit a sufficient amount of electric power over a long distance as its feature. With such characteristics, the magnetic field resonance method has particularly received attention among these four methods. In the magnetic field resonance method, a one-to-N power transmission method using the characteristic of long-distance power transmission has been discussed (see, e.g., Japanese Patent Application Laid-Open No. 2009-136132). The one-to-N power transmission method enables a power transmitting apparatus to wirelessly transmit electric power to a plurality of power receiving apparatuses.

The one-to-N power transmission includes a simultaneous power supply method and a time-division power supply method. In the simultaneous power supply method, the power transmitting apparatus simultaneously supplies electric power to the plurality of power receiving apparatuses, whereas in the time-division power supply method, the power transmitting apparatus sequentially supplies electric power to each of the power receiving apparatuses. The power receiving apparatus includes a power storage device such as a secondary battery mounted therein. The power receiving apparatus stores power in the power storage device using any of the simultaneous power supply method and the time-division power supply method. Among power storage devices, the secondary battery in particular needs to avoid being overcharged, over-discharged, and a rise in ambient temperature thereof. In such a non-contact power supply method, therefore, both of the power transmitting apparatus and the power receiving apparatus need to have functions of stopping power supply in case of abnormality.

The wireless power consortium (WPC) has developed a non-contact charging standard called “Qi”. With the “Qi” standard, a method for stopping the power supplied to a power receiving apparatus is discussed. According to this method, a power transmitting apparatus stops supplying the power in response to a request from the power receiving apparatus. Moreover, Japanese Patent Application Laid-Open No. 2012-44735 discusses a power supply stop method performed by a power receiving apparatus. According to this method, in a case where the power receiving apparatus detects any abnormality while electric power is being supplied, the power receiving apparatus stops the power supplied thereto. Japanese Patent Application Laid-Open No. 2012-44735 also discusses a method performed by a power transmitting apparatus which supplies power to a plurality of power receiving apparatuses using a time-division power supply method. In a case where one of the plurality of power receiving apparatuses stops the power supplied thereto, the power transmitting apparatus performs shift processing so that the power is supplied to another power receiving apparatus.

However, there are cases where the power transmitting apparatus is a cause of a power supply abnormality. In such a case, a similar abnormality may occur again if the power transmitting apparatus continues the power supply processing. The reoccurrence of the abnormality is not desirable.

SUMMARY

Aspects of the present invention are generally directed to a configuration for enabling appropriate processing to be performed in a case where an abnormality in power transmission occurs.

According to an aspect of the present invention, a power transmitting apparatus, which simultaneously or sequentially supplies electric power to a plurality of power receiving apparatuses in a wireless manner, includes a power transmitting unit configured to transmit electric power to the power receiving apparatuses, a reception unit configured to receive a power transmission end request and an abnormality content regarding power transmission from a first power receiving apparatus among the plurality of power receiving apparatuses, and a power transmission determination unit configured, based on the abnormality content, to determine whether to stop power transmission to the power receiving apparatuses which have not completed power transmission thereto and are other than the first power receiving apparatus among the plurality of power receiving apparatuses.

DESCRIPTION OF THE EMBODIMENTS

Various exemplary embodiments will be described in detail below with reference to the drawings.

FIG. 1is a diagram illustrating an electric power transmission system that includes a power transmitting apparatus10and a plurality of power receiving apparatuses20. The power transmitting apparatus10wirelessly supplies electric power to the power receiving apparatus20. That is, the electric power is supplied to the power receiving apparatus20in a non-contact manner. Moreover, the power transmitting apparatus10performs data communications with the power receiving apparatus20, which are needed for the supply of power. The power receiving apparatus20wirelessly receives the electric power supplied from the power transmitting apparatus10. Moreover, the power receiving apparatus20performs the data communications needed for the supply of power with the power transmitting apparatus10. In a power supply area30illustrated inFIG. 1, the power transmitting apparatus10can supply power to the power receiving apparatus20. The power supply area30is a range defined based on a power transmission capacity of the power transmitting apparatus10. In a communication area40, the data communications can be executed between the power transmitting apparatus10and the power receiving apparatus20.

A relationship between the power supply area30and the communication area40is described. The power supply area30is smaller than the communication area40. More specifically, the power supply area30is included in the communication area40. As illustrated inFIG. 1, in a case where a plurality of power receiving apparatuses20is provided in the power supply area30, the power transmitting apparatus10can wirelessly supply electric power to the plurality of power receiving apparatuses20. The power transmitting apparatus10can sequentially and wirelessly supply power (transmit power) to the plurality of power receiving apparatuses20using a time-division power supply method. Moreover, the power transmitting apparatus10can simultaneously and wirelessly supply power to the plurality of power receiving apparatuses20using a simultaneous power supply method.

FIG. 2is a diagram illustrating the power transmitting apparatus10. InFIG. 2, a solid line indicates an exchange of data, whereas a dotted line indicates the supply of electric power. The power transmitting apparatus10includes a control unit110, a wireless transmission unit120, a wireless reception unit130, an alternating current (AC) power source140, and a power supply unit150. The control unit110controls the power transmitting apparatus10. The control unit110includes a central processing unit (CPU)111, a read only memory (ROM)112, a random access memory (RAM)113, a hard disk drive (HDD)114, and a user interface (UI)115. The control unit110is connected to the wireless transmission unit120and the wireless reception unit130via an internal bus.

The CPU111processes various data, and controls the power transmitting apparatus10. The ROM112is a non-volatile storage medium, and stores a boot program to be used by the CPU111. The RAM113is a volatile storage medium, and temporarily stores data and programs to be used by the CPU111. The HDD114is a non-volatile storage medium, and stores an operating system (OS) and applications to be used by the CPU111. The UI115is an operation input unit for receiving an operation input from a user. Moreover, the UI115is a display unit for displaying various pieces of information. For example, the UI115includes a liquid crystal display unit and a touch panel. The CPU111detects a press on the touch panel.

The wireless transmission unit120wirelessly transmits electric power to the power receiving apparatus20. The wireless power transmission unit120includes a communication circuit121, a power transmission circuit122, a diplexer123, a power transmission coil124, and a power transmission control unit125. The communication circuit121generates a modulation signal for performing communications. The power transmission circuit122generates a modulation signal for transmission of electric power. The diplexer123combines the modulation signal generated by the communication circuit121and the modulation signal generated by the power transmission circuit122. The power transmission coil124transmits the modulation signal combined by the diplexer123to the power receiving apparatus20. The power transmission control unit125controls, based on a control instruction from the control unit110, start and stop of the power transmitted by the power transmission circuit122.

The wireless reception unit130receives data from the power receiving apparatus20. The wireless reception unit130includes a power reception coil131, a reception circuit132, and a demodulation circuit133. The power reception coil131receives a modulation signal for performing communications from the power receiving apparatus20. The reception circuit132receives the modulation signal received by the power reception coil131. The demodulation circuit133demodulates the modulation signal received by the power reception coil131. The AC power source140supplies an AC voltage to the power transmission coil124and the power supply unit150. The power supply unit150converts the AC voltage supplied by the AC power source140into a direct current (DC) voltage, and supplies the DC voltage to the control unit110, the wireless transmission unit120, and the wireless reception unit130. A function and processing of the power transmitting apparatus10are performed by reading and executing the program stored in the ROM112or the HDD114by the CPU111.

FIG. 3is a diagram illustrating the power receiving apparatus20. InFIG. 3, a solid line indicates an exchange of data, whereas a dotted line indicates the supply of electric power. The power receiving apparatus20includes a control unit210, a wireless transmission unit220, and a wireless reception unit230. The control unit210controls the power receiving apparatus20. The control unit210includes a CPU211, a ROM212, a RAM213, an HDD214, and a UI215. The control unit210is connected to the wireless transmission unit220and the wireless reception unit230via an internal bus. The CPU211processes various data, and controls the power receiving apparatus20. The ROM212is a non-volatile storage medium, and stores a boot program to be used by the CPU211. The RAM213is a volatile storage medium, and temporarily stores data and programs to be used by the CPU211. The HDD214is a non-volatile storage medium, and stores an OS and applications to be used by the CPU211. The UI215displays various information to a user, and receives various instructions from the user.

The wireless transmission unit220transmits data to the power transmitting apparatus10. The wireless transmission unit220includes a communication circuit221and a power transmission coil222. The communication circuit221generates a modulation signal for performing communications. The power transmission coil222transmits the modulation signal generated by the communication circuit221to the power transmitting apparatus10. The wireless reception unit230wirelessly receives electric power from the power transmitting apparatus10. The wireless reception unit230includes a power reception coil231, a diplexer232, a reception circuit233, a demodulation circuit234, a rectifying circuit235, a voltage stabilization circuit236, a battery237, a power reception monitor238, a temperature sensor239, a battery monitoring circuit240, and a load detection circuit241.

The power reception coil231receives a modulation signal from the power transmitting apparatus10. The diplexer232divides the modulation signal received by the power reception coil231into two signals, that is, a modulation signal for performing communications and a modulation signal for transmission of electric power. The reception circuit233receives the modulation signal for performing communications out of the signals divided by the diplexer232. The demodulation circuit234demodulates the modulation signal received by the reception circuit233. The rectifying circuit235generates a DC voltage by rectifying the modulation signal for transmission of electric power, the modulation signal being divided by the diplexer232. The voltage stabilization circuit236stabilizes the DC voltage generated by the rectifying circuit235.

The battery237receives the voltage stabilized by the voltage stabilization circuit236, and accumulates electric power. Moreover, the battery237supplies a DC voltage to the control unit210, the wireless transmission unit220, and the wireless reception unit230based on the accumulated electric power. The power reception monitor238monitors the voltage and the current received by the power reception coil231. The power reception monitor238inputs an overvoltage signal251to the control unit210if the voltage being monitored thereby exceeds a threshold value that is set beforehand. The power reception monitor238inputs an overcurrent signal252to the control unit210if the current being monitored thereby exceeds a threshold value that is set beforehand.

The temperature sensor239monitors temperature of each of the power reception coil231, the battery237, and the wireless reception unit230. The temperature sensor239notifies the control unit210of a temperature anomaly signal253if the temperature being monitored thereby exceeds a threshold value that is set beforehand. The battery monitoring circuit240monitors the voltage stored in the battery237. The battery monitoring circuit240inputs a full-charge signal254to the control unit210if the current being monitored thereby reaches a threshold value that is set beforehand. The full-charge signal254indicates that the battery237is fully charged. Moreover, the battery monitoring circuit240inputs an overcharge signal255if the voltage being monitored thereby exceeds a threshold value that is set beforehand.

The load detection circuit241detects the load applied to the battery237during power reception. If the battery237is not fully charged, and a load is not detected during the power reception, the load detection circuit241inputs a non-load signal256to the control unit210. Moreover, if a charge amount charged to the battery237exceeds a threshold value that is set beforehand, the load detection circuit241inputs an overload signal257to the control unit210. A function and processing of the power receiving apparatus20are performed by reading and executing the program stored in the ROM212or the HDD214by the CPU211. The function and processing the power receiving apparatus20will be described below.

FIG. 4is a diagram illustrating one example of a superframe. The electric power transmission system according to the present exemplary embodiment performs power transmission processing by repeatedly using the superframes as illustrated inFIG. 4. One superframe includes a period S101(an association period), a period S102(an electric power transmission preparation period), and a period S103(an electric power transmission period). Each of the periods is variable. In the period S101, the power transmitting apparatus10checks device identification (ID) and the necessity of electric power with respect to the power receiving apparatus20. When the power transmitting apparatus10receives the device ID and a notification of the power necessity from the power receiving apparatus20, the period S101is shifted to the period S102. A time in which the period S101is shifted to the period S102is also variable.

In the period S102, the power transmitting apparatus10can transmit a data request to the power receiving apparatus20. With the data request, the power transmitting apparatus10can request device ID of the power receiving apparatus20. The power receiving apparatus20can transmit an acknowledgement as a response to the data request from the power transmitting apparatus10. The power receiving apparatus20transmits an acknowledgement including the device ID with respect to the device ID request. Each length of the response frame and the acknowledgement frame is variable. When the period S102is finished, the processing proceeds to the period S103. A time in which the period S102is shifted to the period S103is also variable. In the period S103, the power transmitting apparatus10transmits electric power to the power receiving apparatus20. In the period S103, the power receiving apparatus20can transmit a frame to the power transmitting apparatus10even if there is not a request frame from the power transmitting apparatus10.

FIG. 5is a diagram illustrating one example of a frame format. In the above superframe, data communications using packets in the frame format as illustrated inFIG. 5are performed. Such data communications enable transmission and reception of data necessary to start power transmission. A frame header310indicates, for example, a destination of data transfer. The frame header310includes ID311, a frame control312, a transmission source address313, a destination address314, and a sequence number315. The ID311is used when the electric power transmission system performs data communications.

The frame control312is information for an exchange of data of the power receiving apparatus20. The frame control312includes a power management3120. The power management3120is data used to check the necessity of electric power. The transmission source address313indicates an address of a transmission source in the data transfer. The destination address314indicates an address of a destination to which data is transferred. The sequence number315indicates a frame number. A frame body320indicates information about a body of the data in the data transfer. The frame body320includes a payload321and a frame check sequence322. The payload321is the body of the data. For example, device ID3210is assigned to the payload321. The device ID3210is identification information of the power receiving apparatus20. The frame check sequence322is data used for an error check on the payload321.

FIG. 6is a sequence diagram illustrating power transmission processing performed between the power transmitting apparatus10and the power receiving apparatus20using a superframe. In the following processing, the data communications for the power transmission are performed using the above-described superframe. In step S201, the power transmitting apparatus10requests ID from the power receiving apparatus20. The power transmitting apparatus10uses the ID311in a frame format. In step S202, the power transmitting apparatus10receives the ID from the power receiving apparatus20. The power receiving apparatus20uses the ID311in the frame format. Subsequently, in step S203, the power transmitting apparatus10checks whether the power receiving apparatus20needs electric power. The power transmitting apparatus10uses the power management3120in the frame format.

In step S204, if the power receiving apparatus20needs electric power, the power receiving apparatus20notifies the power transmitting apparatus10of the necessity of power. In step S204, if electric power is not needed, the power receiving apparatus20notifies the power transmitting apparatus10of the unnecessity of power. The power receiving apparatus20uses the power management3120in the frame format. The power transmitting apparatus10determines the power receiving apparatus20as a power transmission target based on the response result including the necessity of receiving electric power. In step S205, the power transmitting apparatus10prepares for the power transmission. Then, the power receiving apparatus20transmits device ID as a response frame to the power transmitting apparatus10. The power receiving apparatus20uses the device ID3210in the frame format.

Subsequently, in step S206, the power transmitting apparatus10transmits power to the power receiving apparatus20(the power transmitting apparatus10performs power transmission processing). In step S207, when the battery237becomes fully charged, the power receiving apparatus20notifies the power transmitting apparatus10of the end of power transmission. The power receiving apparatus20uses the power management3120in the frame format. Thus, the data communications for the power transmission using one superframe is finished. Accordingly, the data is transmitted and received within the superframe, thereby performing the data communications for the wireless power transmission.

FIG. 7is a diagram illustrating a processing unit700of the power receiving apparatus20. The processing unit700includes a detection signal receiving unit701, a frame generation unit702, and a communication control unit703. The detection signal receiving unit701receives a detection signal. The detection signal is an overvoltage signal251, an overcurrent signal252, a full-charge signal254, an overcharge signal255, a temperature anomaly signal253, a non-load signal256, or an overload signal257. The frame generation unit702generates a frame of an end request for power transmission based on the detection signal received by the detection signal receiving unit701. The end request is information for requesting that the power transmission performed by the power transmitting apparatus10should be finished. The frame generation unit702writes in the power management3120of the frame a content to be notified to the power transmitting apparatus10based on the detection signal. The notification content is information indicating a reason for transmitting the end request. Moreover, the frame generation unit702generates the frame body320and the frame header310other than the power management3120, and acquires the end request frame. In step S207illustrated inFIG. 6, the communication control unit703transmits the end request frame to the power transmitting apparatus10through the wireless transmission unit220.

FIG. 8is a diagram illustrating the notification contents written in the power management3120. The notification contents include an overvoltage801, an overcurrent802, a temperature anomaly803, a full-charge804, an overcharge805, a non-load806, and an overload807. These notification contents801through807are generated when the overvoltage signal251, the overcurrent signal252, the temperature anomaly signal253, the full-charge signal254, the overcharge signal255, the non-load signal256, and the overload signal257are received respectively. When the detection signal receiving unit701receives the overvoltage signal251, the frame generation unit702generates the overvoltage801. Then, the generated overvoltage801is written in the power management3120. Similarly, when the detection signal receiving unit701receives the overcurrent signal252, the temperature anomaly signal253, and the full-charge signal254, the frame generation unit702generates the overcurrent802, the temperature anomaly803, and the full-charge804, respectively. Each of these generated notification contents is written in the power management3120. Moreover, when the detection signal receiving unit701receives the overcharge signal255, the non-load signal256, and the overload signal257, the frame generation unit702generates the overcharge805, the non-load806, and the overload807, respectively. Each of these generated notification contents is written in the power management3120. The power management3120may include information other than the notification contents.

FIG. 9is a diagram illustrating a processing unit900of the power transmitting apparatus10. The processing unit900includes a communication control unit901, a notification content determination unit902, a number-of-failures storage unit903, a stop determination unit904, and a power transmission instruction unit905. The communication control unit901receives an end request frame from the power receiving apparatus20through the wireless reception unit130. The notification content determination unit902determines the notification content written in the power management3120of the frame. More specifically, the notification content determination unit902determines whether the notification content indicates any of normal completion of charging, an abnormality in the power receiving apparatus20, or an abnormality in the power transmitting apparatus10.

In the present exemplary embodiment, in a case where the notification content is the full-charge804, the notification content determination unit902determines that the charging is completed normally. In a case where the notification content is the overvoltage801or the overcurrent802, the notification content determination unit902determines there is an abnormality in the power transmitting apparatus10. In a case where the notification content is the temperature anomaly803, the overcharge805, the non-load806, or the overload807, the notification content determination unit902determines that there is an abnormality in the power receiving apparatus20. The number-of-failures storage unit903stores the number of times that the notification content regarding the abnormality in the power receiving apparatus20is received as the number of failures. The notification content determination unit902writes the number of failures in the number-of-failures storage unit903. That is, in a case where the notification content indicates the abnormality in the power receiving apparatus20, the notification content determination unit902adds 1 to a value of the number of failures stored in the number-of-failures storage unit903.

The stop determination unit904compares the number of failures stored in the number-of-failures storage unit903with a threshold value, and determines whether to stop power transmission based on the comparison result. The threshold value is stored, for example, in the ROM112beforehand. The threshold value can be optionally set by a user through the UI115. The power transmission instruction unit905instructs the power transmission control unit125to start and stop power transmission. The power transmission instruction unit905instructs the power transmission control unit125to stop power transmission not only to the power receiving apparatus20to which the power is being transferred from the power transmitting apparatus10, but also to a power receiving apparatus20that is scheduled to receive the power from the power transmitting apparatus10.

FIG. 10is a flowchart illustrating end request transmission processing performed by the power receiving apparatus20. The end request transmission processing is executed while the power receiving apparatus20is receiving the power supplied from the power transmitting apparatus10. That is, this processing is executed in the electric power transmission period S103. In step S1001, the detection signal receiving unit701of the power receiving apparatus20waits for a detection signal. If the detection signal receiving unit701receives the detection signal (YES in step S1001), the operation proceeds to step S1002. In step S1002, the frame generation unit702generates a notification content to be written in the power management3120based on the detection signal received in step S1001by the detection signal receiving unit701.

In step S1003, the frame generation unit702writes the notification content in the power management3120, and generates an end request frame by generating the frame header310and the frame body320. Subsequently, in step S1004, the communication control unit703transmits the end request frame generated in step S1003by the frame generation unit702to the power transmitting apparatus10through the wireless transmission unit220. Thus, the end request transmission processing by the power receiving apparatus20is completed. With the end request transmission processing, therefore, the power receiving apparatus20transmits the notification content indicating a reason for end request transmission along with the end request to the power transmitting apparatus10.

FIG. 11is a flowchart illustrating power transmission stop processing performed when the power transmitting apparatus10supplies electric power in a simultaneous manner. The simultaneous power supply represents a power supply method enabling electric power to be concurrently supplied to a plurality of power receiving apparatuses20as power transmission targets in an electric power transmission period within one superframe. In step S1101, the communication control unit901of the power transmitting apparatus10receives an end request frame from one of the plurality of power receiving apparatuses20to which power is being transmitted (the communication control unit901performs reception processing). The end request frame is received through the wireless reception unit130. In step S1102, the power transmission instruction unit905instructs the power transmission control unit125to stop power transmission to the power receiving apparatus20of a transmission source of the end request frame. Accordingly, the power transmission control unit125stops power transmission to the power receiving apparatus20of the transmission source of the end request frame.

Subsequently, in step S1103, the notification content determination unit902checks the notification content written in the power management3120in the end request frame. If the notification content is full-charge (YES in step S1103), that is, the notification content indicates that the charging is completed normally, the operation proceeds to step S1104. In step S1104, the power transmission instruction unit905checks whether power transmission to all the power receiving apparatuses20as power transmission targets in the superframe in execution is finished. That is, the power transmission instruction unit905checks whether power transmission to the power receiving apparatuses20to which power is simultaneously transmitted is completed. If power transmission to all the power receiving apparatuses20is finished (YES in step S1104), the power transmission stop processing ends. On the other hand, if there is a power receiving apparatus20that has not completed power transmission thereto (NO in step S1104), the operation returns to step S1101.

If the notification content determination unit902determines that the notification content is other than full-charge, that is, the notification content indicates an abnormality in the power transmission (NO in step S1103), the operation proceeds to step S1105. If the notification content determination unit902determines that the notification content is an overvoltage or an overcurrent, that is, there is an abnormality in the power transmitting apparatus10(YES in step S1105), the operation proceeds to step S1108. In step S1108, the power transmission instruction unit905determines that power transmission to all the power receiving apparatuses20as the power transmission targets in the superframe in execution should be stopped. That is, power transmission to all the power receiving apparatuses20to which power is being transmitted should be stopped (the power transmission instruction unit905performs power transmission determination processing). Accordingly, the power transmission instruction unit905instructs the power transmission control unit125to stop power transmission to all the power receiving apparatuses20to which power is being transmitted. That is, in a case where the abnormality content indicates that there is an abnormality in the power transmitting apparatus10, the notification content determination unit902determines to stop power transmission to all the power receiving apparatuses20which have not completed power transmission thereto. Then, the notification content determination unit902issues an instruction to the power transmission instruction unit905. Accordingly, the power transmission instruction unit905instructs the power transmission control unit125to stop power transmission to all the power receiving apparatuses20based on the instruction from the notification content determination unit902.

If the notification content is any of a temperature anomaly, an overcharge, a non-load, or an overload, that is, there is an abnormality in the power receiving apparatus20(NO in step S1105), the operation proceeds to step S1106. In step S1106, the notification content determination unit902adds 1 to a value of the number of failures stored in the number-of-failures storage unit903, and stores the resultant value as the number of failures in the number-of-failures storage unit903(the notification content determination unit902performs number-of-times management processing). In step S1107, the stop determination unit904compares the number of failures with a threshold value. If the number of failures is less than the threshold value (NO in step S1107), the operation proceeds to step S1104. If the number of failures is the threshold value or greater (YES in step S1107), the operation proceeds to step S1108. That is, if the number of failures is the threshold value or greater, the power transmission instruction unit905stops power transmission to all the power receiving apparatuses20of the power transmission targets (except for the power receiving apparatus20of a transmission source of the end request). Accordingly, the power transmitting apparatus10completes the power transmission stop processing in the simultaneously power supply.

FIG. 12is a flowchart illustrating the power transmission stop processing performed when the power transmitting apparatus10supplies power in a time-division manner. The time-division power supply represents a power supply method enabling electric power to be sequentially supplied to a plurality of power receiving apparatuses20as power supply targets in an electric power transmission period within one superframe. The power transmission stop processing illustrated inFIG. 12is described by referring to the difference between the time-division power supply inFIG. 12and the simultaneous power supply described inFIG. 11. The processing similar to that in the power transmission stop processing in the simultaneous power supply inFIG. 11is given the same reference numeral.

If the notification content determination unit902determines that the notification content is full-charge (YES in step S1103), the operation proceeds to step S1201. In step S1201, the power transmission instruction unit905checks whether power transmission to all the power receiving apparatuses20as power transmission targets in the superframe in execution is finished. That is, the power transmission instruction unit905checks whether power transmission to all the power receiving apparatuses20to which power should be sequentially transmitted in a time-division manner is finished. If power transmission to all the power receiving apparatuses20is finished (YES in step S1201), the power transmission stop processing ends. On the other hand, if there is a power receiving apparatus20that has not completed power transmission thereto (NO in step S1201), the operation proceeds to step S1202. In step S1202, the power transmission instruction unit905instructs the power transmission control unit125to start power transmission to a next power receiving apparatus20. The next power receiving apparatus20is an apparatus scheduled to receive power after the power receiving apparatus20of the end request transmission source receives the power.

If the number of failures is less than the threshold value (NO in step S1107), the operation proceeds to step S1201. If the number of failures is the threshold value or greater (YES in step S1107), the operation proceeds to step S1203. In step S1203, the power transmission instruction unit905stops power transmission to the power receiving apparatus20having not completed power transmission thereto in the frame in execution. The power receiving apparatus20having not completed power transmission thereto is an apparatus that was scheduled to sequentially receive power after the next power receiving apparatus20of the end request transmission source in the superframe in execution. Thus, the power transmitting apparatus10completes the power transmission stop processing in the time-division power supply.

Therefore, the power transmitting apparatus10according to the present exemplary embodiment stops power transmission to the power receiving apparatus20of the end request transmission source based on the notification content received from the power receiving apparatus20. In addition, the power transmitting apparatus10determines, based on the notification content received from the power receiving apparatus20, whether to stop power transmission to other power receiving apparatuses20that have not completed power transmission thereto. Upon receipt of an end request due to an abnormality in the power transmitting apparatus10, the power transmitting apparatus10stops power transmission to all the power receiving apparatuses having not completed power transmission thereto. Moreover, the power transmitting apparatus10stops power transmission to all the power receiving apparatuses20having not completed power transmission thereto according to the number of abnormalities that have occurred in the power receiving apparatus20. This can prevent a failure of the power receiving apparatus20. That is, in a case where an abnormality relating to the power transmission occurs, the electric power transmission system according to the present exemplary embodiment can appropriately deal with the abnormality.

Other Embodiments

While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that these exemplary embodiments are not seen to be limiting. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No. 2013-100390 filed May 10, 2013, which is hereby incorporated by reference herein in its entirety.