Patent Application
20150061398
An embodiment described herein relates to a power transmitting apparatus, a power receiving apparatus, and a wireless power transmission system.
In a communication apparatus, a long-term communication interruption due to a fault or the like and a temporary communication interruption due to interference, noise, or the like occur. A wireless power transmission apparatus includes a radio communication device for wireless power transmission control. However, when the radio communication device is interrupted, it is necessary to stop power transmission in order to secure safety. On the other hand, a method of duplicating communicating means as a technique for improving the reliability of communication is widely known. Further, in the wireless power transmission apparatus, there is known a method of providing two communicating means in which one of the communicating means performs communication between coils for power transmission, although the method is not a technology for improving reliability. In the wireless power transmission apparatus, by using the inter-coil communication, it is possible to save a space when the wireless power transmission apparatus includes a plurality of communicating means.
However, in the latter method, which is a related art, transmission and reception of initial setting for a radio communication device for contents (transmission and reception of an SSID or the like in a wireless LAN) is performed in the inter-coil communication. Communication of transmission control for wireless power transmission is performed by the inter-coil communication. In particular, when load modulation used in, for example, RFID is applied when the inter-coil communication is performed during the wireless power transmission, power transmission efficiency is deteriorated because load impedance on a power receiving side changes. When transmitting and receiving units for the inter-coil communication has broken down, power transmission is stopped.
In this way, in the wireless power transmission apparatus in the past, the wireless power transmission is stopped during a communication interruption and the power transmission efficiency is deteriorated during control of the wireless power transmission.
According to some embodiments, there is provided a power transmitting apparatus including: a first antenna, a first communicating unit, a power supply unit, a second antenna, a second communicating unit, a measuring unit and a control unit.
The first communicating unit performs communication with a power receiving apparatus using the first antenna.
The power supply unit generates electric power.
The second antenna transmits the electric power generated by the power supply unit to the power receiving apparatus.
The second communicating unit performs communication with the power receiving apparatus using the second antenna.
The measuring unit measures first communication quality of the first communicating unit and second communication quality of the second communicating unit.
The control unit communicates, while power transmission to the power receiving apparatus is performed, transmission control information with the power receiving apparatus using the first communicating unit or the second communicating unit and controls the power transmission to the power receiving apparatus on the basis of the transmission control information.
The control unit selects any one of the first communicating unit and the second communicating unit according to the first communication quality and the second communication quality to communicate the transmission control information.
An embodiment will be explained in detail below with reference to the accompanying drawings.
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According to the embodiment, the wireless power transmission system performs power transmission control and safety maintenance control, when safety is spoiled, for example, in breakage of an apparatus, by using radio communication. The transmission control adjusts electric power, voltage and electric current to what a load of the power receiving apparatus requests. As transmission control information exchanged in the transmission control, information described below is conceivable.
A wireless power transmission apparatus (which represents a power transmitting apparatus, a power receiving apparatus or both of them) includes a plurality of blocks such as a power supply, an inverter, a coil, a rectifier, and a load. Electric power, electric current, and voltage information is monitored in necessary places of the respective blocks. The “respective measurement points” indicate places where electric power, electric currents and voltages are measured in the respective blocks or among the blocks. The transmission control information exchanged before power transmission is performed is called as pre-power transmission information and the transmission control information exchanged during which power transmission is performed is called as power transmission information.
Safety control information used in the safety maintenance control is listed below.
Note that the information used for the control is not limited to the above. Any information can be applied as long as the information is used for control for maintaining safety. The safety control information may be defined as being included in the transmission control information.
A difference between the left diagram and the right diagram of
First, a list of control items in the power transmitting apparatus for wireless power transmission according to the embodiment is shown in
The first operation example of the embodiment in the first configuration example is explained. In the first operation example, the power transmitting apparatus for wireless power transmission transitions to any one of the states shown in
State 1 (normal mode): communicating unit 1=link stable communicating unit 2=link stable
State 2 (interruption 1 mode): communicating unit 1 interrupted communicating unit 2=link stable
State 3 (interruption 2 mode): communicating unit 1=link stable communicating unit 2=interrupted
State 4 (full interruption mode): communicating unit 1=interrupted communicating unit 2=interrupted
Operation procedures in the respective states are shown in the figures.
An example of a flowchart at the time of startup of wireless power transmission in the normal mode is shown in
As a first procedure, the power transmitting apparatus performs apparatus detection for searching for a power receiving apparatus (S101). For the apparatus detection, the communicating unit 1 may be used or the communicating unit 2 may be used. An advantage of performing the apparatus detection using the communicating unit 1 is that, for example, it is possible to detect a target power receiving apparatus from a relatively wide range compared with the apparatus detection using the communicating unit 2. However, for the detection of a power receiving apparatus, it is necessary to always supply electric power to the communicating unit 1. Therefore, there is a disadvantage that consumed power increases. An advantage of performing the apparatus detection using the communicating unit 2 is that, for example, in particular, it is possible to reduce consumed power on a power receiving apparatus side. However, as explained above, the communicating unit 2 has an extremely narrow communicable range, there is a disadvantage that an apparatus detectable range is narrow. If a power receiving apparatus is found (Yes in S102), the power transmitting apparatus shifts to the next procedure. If a power receiving apparatus is not found (No in S102), the power transmitting apparatus repeats the apparatus detection. The apparatus detection may be always performed or may be cyclically performed. When the apparatus detection is cyclically performed, consumed power can be reduced compared with power consumed when the apparatus detection is always performed. Note that the apparatus detection may be performed by means other than the communicating unit 1 and the communicating unit 2. For example, a sensor, a camera, or a separate communication apparatus may be used.
When a power receiving apparatus is detected by the apparatus detection, the power transmitting apparatus performs authentication of the power receiving apparatus in order to determine whether the power receiving apparatus is a malicious apparatus having a purpose of a power theft or an obstacle (S103). As the apparatus authentication, because of an advantage that a communicable range is limited when the communicating unit 2 is used, it is possible to perform authentication with high confidentiality. When the apparatus authentication is successful (Yes in S104), the power transmitting apparatus shifts to the next procedure. When the apparatus authentication is unsuccessful (No in S104), the power transmitting apparatus transitions to an error state. Rather than transitioning to the error state when the apparatus authentication is unsuccessful once, the power transmitting apparatus may transition to the error state when the apparatus authentication is continuously unsuccessful a plurality of times. Not that the power transmitting apparatus may perform the apparatus authentication simultaneously with the apparatus detection or before the apparatus detection.
When the apparatus authentication ends, the power transmitting apparatus performs alignment (S105). The alignment is a procedure for correcting a positional relation between the power transmitting apparatus and the power receiving apparatus for improving power transmission efficiency. When a power transmission characteristic acquired in the communicating unit 2 is used for the alignment, it is desirable to use the communicating unit 2. However, the alignment can be realized by the communicating unit 1 as well. Note that the alignment performed using the communicating unit 1 or 2 could be sometimes unnecessary. For example, when a setting position of the power receiving apparatus is explicitly marked in a power transmitting apparatus main body and a user arranges the power receiving apparatus in the setting position, communication is unnecessary and the user performs the alignment. As shown in
When the alignment ends, the power transmitting apparatus performs to exchange pre-power transmission information and safety control information necessary at the start of power transmission (S107). The information is transmitted using the communicating unit 1. In general, the communicating unit 1 has a high transmission rate compared with the communicating unit 2. Therefore, when the communicating unit 1 is used, the power transmitting apparatus can shift to the start of power transmission more quickly than when the communicating unit 2 is used.
When the exchange of the pre-power transmission information and the safety control information ends, the power transmitting apparatus transmits a power transmission start notification (S108) and starts power transmission (S109). The power transmitting apparatus may transmit the power transmission start notification using either the communicating unit 1 or the communicating unit 2. The power transmitting apparatus may start the power transmission without transmitting the power transmission start notification.
Note that, for the position detection, the alignment, and the obstacle detection shown in
A flowchart during power transmission of wireless power transmission in the normal mode is shown in
During the wireless power transmission, the power transmitting apparatus cyclically or suddenly performs a check of a transmission state, safety control, and radio communication of power transmission information and safety control information for charging control to a battery (S201). This is performed using the communicating unit 1. During power transmission, when communication is performed in the communicating unit 2 using, in particular, load modulation, deterioration in power transmission efficiency is caused. Therefore, it is desirable to use the communicating unit 1. When it is necessary to stop the power transmission (Yes in S202) or some error occurs, the power transmitting apparatus sends a power transmission stop notification and stops the power transmission (S203).
A flowchart at the time of startup of wireless power transmission in the interruption 1 mode is shown in
In the interruption 1 mode, the control is executed up to the power transmission start according to the same procedures as the procedures in the normal mode. However, the interruption 1 mode is different from the normal mode in that all the kinds of information exchanged by the communicating unit 1 in the normal mode are exchanged by the communicating unit 2.
First, in apparatus detection (S301), the method of detecting a power receiving apparatus using the communicating unit 2, a sensor, a camera, a separate communication apparatus, or the like may be used. Any method other than the detection by the communicating unit 1 can be applied. If a power receiving apparatus is found (Yes in S302), the power transmitting apparatus shifts to the next procedure. If a power receiving apparatus is not found (No in S302), the power transmitting apparatus repeats the apparatus detection.
Subsequently, the power transmitting apparatus performs apparatus authentication (S303) using the communicating unit 2 as in the normal mode. When the apparatus authentication is successful (Yes in S304), the power transmitting apparatus shifts to the next procedure. When the apparatus authentication is unsuccessful (No in S304), the power transmitting apparatus transitions to an error state. Note that, rather than transitioning to the error state when the apparatus authentication is unsuccessful once, the power transmitting apparatus may transition to the error state when the apparatus authentication is continuously unsuccessful a plurality of times. The power transmitting apparatus may perform the apparatus authentication simultaneously with the apparatus detection or before the apparatus detection.
When the apparatus authentication ends, the power transmitting apparatus performs alignment (S305). When a power transmission characteristic acquired by the communicating unit 2 is used for the alignment, it is desirable to use the communicating unit 2. However, any method of aligning a position using an apparatus other than the communicating unit 1 such as a sensor, a camera, or a communication apparatus can be applied. Note that the alignment performed using the communicating unit 2 or other apparatuses could be sometimes unnecessary. For example, when a setting position of the power receiving apparatus is explicitly marked in a power transmitting apparatus main body and a user arranges the power receiving apparatus in the setting position, communication is unnecessary and the user performs the alignment. The order of the alignment may be interchanged with the order of the apparatus detection and the apparatus authentication performed at the pre-stage of the alignment. It is also possible to perform, at the time of the alignment, calibration necessary at the time of power transmission start.
When the alignment ends (Yes in S306), subsequently, for power transmission preparation, the power transmitting apparatus exchanges pre-power transmission information and safety control information necessary at the start of power transmission (S307). The information is transmitted using the communicating unit 2. At this point, information for notifying that the communicating unit 1 is interrupted and basic information for using the wireless power transmission and the inter-coil communication in common are exchanged in advance. Examples of the basic information include several items described below.
The communication timing is necessary to separate the wireless power transmission and the inter-coil communication, for example, when the wireless power transmission and the inter-coil communication are shared in a time-division manner.
In
The initial inter-coil communication can be carried out according to the communication timing. However, the inter-coil communication is cyclically carried out according to a data type and a data cycle exchanged in advance. The data cycle is sometimes different depending on the data type. In that case, a plurality of data types need to be mixed and transmitted. In
When a plurality of kinds of data types having different communication timings and data cycles are simultaneously transmitted, it is necessary to perform communication according to the data cycles of the respective data types as shown in
Information concerning the data type and the data cycle is extremely important parameters in the interruption 1 mode. For example, the pre-power transmission information and the safety control information are included as types of data in the normal mode. In the interruption 1 mode, a data type is designated at the time of startup and only designated information is exchanged during power transmission (i.e., an information amount to be communicated is reduced; conversely, the information amount is increased in the normal mode). Consequently, it is possible to minimize resources used for communication and carry out power transmission control while minimizing deterioration in the power transmission efficiency. Note that, as data types used in the interruption 1 mode, for example, electric power, electric current, and voltage information at respective measurement points, resistance information of a load or, when the load is a battery, charging information, and the like are included. However, the data types are not limited to such information. It is possible to improve the power transmission efficiency by saving information to be communicated as much as possible. Further, at this point, the data cycle is also exchanged. Basically, any control is performed according to a certain specific cycle and communication concerning the control is cyclically performed on the basis of the cycle. In particular, in the case of the wireless power transmission apparatus, the power transmitting apparatus requests necessary data and the power receiving apparatus returns data corresponding to the request. The exchange of the data is carried out at a fixed cycle. At this point, a cycle of data and a type of the data called from the power transmitting apparatus are exchanged before the start of power transmission. Consequently, it is possible to acquire data necessary for the control from the power receiving apparatus without performing a data request from the power transmitting apparatus. In other words, it is possible to realize transmission control for the wireless power transmission according to cyclic transmission of data in one-way from the power receiving apparatus. Consequently, it is possible to reduce resources necessary for communication and improve the power transmission efficiency.
When the exchange of the pre-power transmission information and the safety control information ends, the power transmitting apparatus transmits a power transmission start notification (S308) and starts power transmission (S309). The power transmitting apparatus also performs the power transmission start notification using the communicating unit 2. The power transmitting apparatus may start the power transmission without transmitting the power transmission start notification.
Note that, in
A flowchart during power transmission of the wireless power transmission in the interruption 1 mode is shown in
The flowchart is different from that in normal mode in that, when restoration of the communicating unit 1 is detected (Yes in S401), the power transmitting apparatus switches the communicating unit to the communicating unit 1 and transitions to the normal mode. When the power transmission information and the safety control information are exchanged (S402), as explained above, the power transmitting apparatus performs exchange of the information on the basis of a data type and a data cycle exchanged before the start of power transmission as explained above. Processing in steps S403 and S404 is the same as the processing in steps S202 and S203 in the normal mode shown in
An example of a procedure in the case of transitioning from another state to the interruption 1 mode during power transmission is shown in
A flowchart at the time of startup of the wireless power transmission in the interruption 2 mode is shown in
As a first procedure, the power transmitting apparatus performs apparatus detection for searching for a power receiving apparatus (S601). For the apparatus detection, the communicating unit 1 may be used or a sensor, a camera, or a separate communication apparatus may be used. If a power receiving apparatus is found (Yes in S602), the power transmitting apparatus shifts to the next procedure. If a power receiving apparatus is not found (No in S602), the power transmitting apparatus repeats the apparatus detection. The apparatus detection may be always performed or may be cyclically performed. When the apparatus detection is cyclically performed, consumed power can be reduced compared with power consumed when the apparatus detection is always performed.
When a power receiving apparatus is detected by the apparatus detection, the power transmitting apparatus performs authentication of the power receiving apparatus in order to determine whether the power receiving apparatus is a malicious apparatus having a purpose of a power theft or a obstacle (S603). The apparatus authentication is performed using the communicating unit 1. When the communicating unit 2 is used, since the communicating unit 2 has a communicable range wider than a communicable range of the communicating unit 1, there are risks of wiretapping and piracy. Therefore, firm security measures may be taken according to necessity. Not that, rather than transitioning to the error state when the apparatus authentication is unsuccessful once, the power transmitting apparatus may transition to the error state when the apparatus authentication is continuously unsuccessful a plurality of times. The power transmitting apparatus may perform the apparatus authentication simultaneously with the apparatus detection or before the apparatus detection.
Note that it can be determined whether the communicating unit 2 is interrupted only when communication is performed by the communicating unit 2 in the apparatus authentication unless the communicating unit 2 is used for the apparatus detection. Therefore, the power transmitting apparatus transitions to the interruption 2 mode at the first stage of the use of the communicating unit 2.
When the apparatus authentication ends (Yes in S604), the power transmitting apparatus performs alignment (S605). For the alignment, the communicating unit 1 may be used. Any method of aligning a position using an apparatus other than the communicating unit 2 such as a sensor, a camera, or a separate communication apparatus can be applied. Note that the alignment could be sometimes unnecessary depending on an application to be applied. For example, when a setting position of the power receiving apparatus is explicitly marked in a power transmitting apparatus main body and a user arranges the power receiving apparatus in the setting position, communication is unnecessary and the user performs the alignment. When the alignment is performed, it is also possible to perform calibration necessary at the time of start of power transmission.
When the alignment ends (Yes in S606), subsequently, the power transmitting apparatus exchanges pre-power transmission information and safety control information necessary at the time of start of power transmission (S607). The information is transmitted using the communicating unit 1. At this point, in the interruption 2 mode, information for notifying the power receiving apparatus that the communicating unit 2 is interrupted may be added.
When the exchange of the pre-power transmission information and the safety control information ends, the power transmitting apparatus transmits a power transmission start notification using the communicating unit 1 (S608) and starts power transmission (S609). The power transmitting apparatus may start the power transmission without transmitting the power transmission start notification.
A flowchart during power transmission of the wireless power transmission in the interruption 2 mode is shown in
When both of the communicating unit 1 and the communicating unit 2 are interrupted, the power transmitting apparatus transitions to the full interruption mode. In this full interruption mode, irrespective of whether the power transmission is started up or being performed, the power transmitting apparatus determines that the power transmitting apparatus is in a power transmission impossible state (S801) and does not perform the wireless power transmission. In this mode, the control unit repeatedly performs a check of communication restoration in both of the communicating unit 1 and the communicating unit 2 (S802, S803, and S804). When any one of or both of the communicating unit 1 and the communicating unit 2 are restored, the power transmitting apparatus transitions to the respective modes (interruption 2, normal, and interruption 1) and performs startup processing or power transmission.
A flowchart until communication restoration in the communicating unit 1 and the communicating unit 2 currently being interrupted in the interruption 1 mode, the interruption 2 mode, and the full interruption mode is shown in
When communication is interrupted in the communicating unit 1 and the communicating unit 2, it is necessary to cyclically check restoration of the communication. Therefore, the elapse of time is counted (S901), and after a fixed time elapses (Yes in S901), the power transmitting apparatus performs a connection request (S902). The connection request indicates, for example, when Bluetooth is used as the communicating unit 1, Page Scan, Inquiry Scan, Page, or Inquiry, and indicates that, for example, when wireless LAN is used, exchange of an authentication key after a check of an SSID is performed. When the connection is successful (Yes in S903), the power transmitting apparatus performs a communication check for a reliability check for communication (S904). When the connection is unsuccessful (No in S903), the power transmitting apparatus stays on standby in a communication interrupted state until the next elapse of time again. Note that, when the communicating unit 2 is interrupted, the power transmitting apparatus may first perform a communication check, which is the next flow, without performing the connection request.
Examples of a communication check method performed when connection is successful include a method of actually performing data communication a plurality of times using the communicating unit 1 and the communicating unit 2 and counting the number of times of communication success. If the number of times of communication success is equal to or larger than a threshold, the power transmitting apparatus determines that reliability of communication can be secured (Yes in S905) and determines that the communicating unit 1 and the communicating unit 2 are restored. The communication is performed a plurality of times because if the communication is performed only once or a few times, it is determined that the communication is restored even when the communication is accidentally successful, and actually, it is likely that a communication environment is extremely unstable because of interference and noise. To prevent this state, a certain threshold is provided to determine restoration of the communication. The threshold can be arbitrarily set according to each system. Note that the above method is desirable as a method of checking the reliability of communication. However, the method is not limited to the above method and other methods can be applied.
In the power transmitting apparatus for wireless power transmission according to the embodiment, in a state in which power transmission needs to be immediately emergently stopped because of an anomaly such as heat generation of the power receiving apparatus, breakage of an apparatus, overvoltage, overcurrent, or the like, it is necessary to perform radio communication in order to notify that the power transmission is emergently stopped. At this point, when the emergency stop of the power supply is notified using the communicating unit 1 in which a general communication standard such as wireless LAN or Bluetooth is used, since a delay is caused by processing in respective protocols or processing by an access control unit such as a MAC layer, it is extremely difficult to satisfy a delay time allowed until the emergency stop. Therefore, in this proposal, when the emergency stop is immediately necessary, an emergency stop signal, which is an example of an anomaly notification signal, is exchanged using the communicating unit 2 in both the normal mode and the interruption 1 mode unless the communicating unit 2 is interrupted. When the communicating unit 2 is used, it is easy to change the configuration of a frame. For example, if a preamble for emergency stop including a code different from a preamble part usually used in the communicating unit 2 is used as a preamble part of a frame as shown in
Rather than using the preamble for emergency stop, it may be regarded that the emergency stop signal is received by the protecting operation for the power transmitting apparatus, the operation of a protection circuit 42 included in the power receiving apparatus in a wireless power transmission system shown in
A second configuration example of the power transmitting apparatus for wireless power transmission according to the embodiment is shown in
In the configuration of the power transmitting apparatus for wireless power transmission shown in
The power transmitting apparatus for wireless power transmission shown in
The configuration of the power transmitting apparatus for wireless power transmission shown in
A second operation example in a second configuration example of the power transmitting apparatus for wireless power transmission according to the embodiment is explained. In the second configuration example, as in the first operation example, control flows different from one another are applied in the four states specified in
For example, in the case of the normal mode, various kinds of setting are performed in the flow shown in
A difference between the left diagram and the right diagram of
Load modulation (backscatter modulation) that is used for RFID and the wireless power transmission system for small power devices, can be applied to the communicating unit 2. In this case, a load modulation circuit for performing the load modulation may be connected to either the front or the back of the rectifier. Although not shown in
A first operation example of the embodiment in the first configuration example is explained. In the first operation example, the power receiving apparatus transitions to any one of the states shown in
State 1 (normal mode): communicating unit 1=link stable communicating unit 2=link stable
State 2 (interruption 1 mode): communicating unit 1=interrupted communicating unit 2=link stable
State 3 (interruption 2 mode): communicating unit 1=link stable communicating unit 2=interrupted
State 4 (full interruption mode): communicating unit 1=interrupted communicating unit 2=interrupted
Operation procedures in the respective states are the same as the operation procedures in the first operation example of the power transmitting apparatus. Therefore, explanation of the operation procedures is omitted.
In the power receiving apparatus for wireless power transmission according to the embodiment, in a state in which power transmission needs to be immediately emergently stopped because of heat generation of the power receiving apparatus, breakage of an apparatus, overvoltage, overcurrent, or the like, it is necessary to perform radio communication in order to notify that the power transmission is emergently stopped. At this point, when the emergency stop of the power supply is notified using the communicating unit 1 in which a general communication standard such as wireless LAN or Bluetooth is used, since a delay is caused by processing in respective protocols or processing by an access control unit such as a MAC layer, it is extremely difficult to satisfy a delay time allowed until the emergency stop. Therefore, in this proposal, when the emergency stop is immediately necessary, an emergency stop signal is exchanged using the communicating unit 2 in both the normal mode and the interruption 1 mode unless the communicating unit 2 is interrupted. When the communicating unit 2 is used, it is easy to change the configuration of a frame. For example, if a preamble for emergency stop including a code different from a preamble part usually used in the communicating unit 2 is used as a preamble part of a frame as shown in
Rather than using the preamble for emergency stop, the protection circuit 42 included in the power receiving apparatus in the wireless power transmission system shown in
Note that changes in a voltage and an electric current on the power transmitting apparatus side at the time of the protection circuit operation are different depending on circuit topologies. Therefore, it is necessary to select an optimum method for determining the protection circuit operation according to each of the topologies. Note that examples of a place where the voltage and electric current changes are measured on the power transmitting apparatus side of the protection circuit operation include a place between the power transmission antenna and the inverter, a place between the power distributing unit and the inverter, and a place between the power supply unit and the inverter. However, besides these places, the place for measuring the voltage and electric current changes may be any place where the protection circuit operation is possible to obtain these changes in the power transmitting apparatus.
A first configuration example of the wireless power transmission system according to the embodiment is shown in
The power transmission-side control unit 34 selects at least one of the power transmission-side communicating unit 1 and the power transmission-side communicating unit 2 and exchanges parameters necessary for control of the wireless power transmission with the power receiving apparatus. Similarly, the power reception-side control unit 44 selects at least one of the power reception-side communicating unit 1 and the power reception-side communicating unit 2 and exchanges parameters necessary for control of the wireless power transmission with the power transmitting apparatus. Load modulation (backscatter modulation) that is used for RFID and the wireless power transmission system for small power devices, can be applied to the power transmission-side communicating unit 2 and the power reception-side communicating unit 2. In this case, in the power transmitting apparatus, the load modulation can be applied to either of the front or the back of the inverter. In the power receiving apparatus, the load modulation can be applied to either of the front or the back of the converter. In the power transmitting apparatus, irrespective of the application of the load modulation, it is also possible to directly connect the inverter and generate a signal using a switch of the inverter. In the power receiving apparatus, the converter may be connected between the rectifier 41 and the protection circuit 42.
In the first configuration example of the wireless power transmission system according to the embodiment, the power transmission-side control unit 34 of the power transmitting apparatus functions as a master and executes various kinds of control for the wireless power transmission and control performed when the power transmission-side and power reception-side communicating units 1 and 2 are interrupted. The power reception-side control unit 44 of the power receiving apparatus functions as a slave and receives a command of the power transmission-side control unit 34 and operates.
First, a list of control items in the wireless power transmission system according to the embodiment is shown in
A first operation example of the embodiment in the first configuration example of the wireless power transmission system according to the embodiment is explained. In the first operation example, the wireless power transmission system transitions to any one of the states shown in
State 1 (normal mode): communicating unit 1=link stable communicating unit 2=link stable
State 2 (interruption 1 mode): communicating unit 1=interrupted communicating unit 2=link stable
State 3 (interruption 2 mode): communicating unit 1=link stable communicating unit 2=interrupted
State 4 (full interruption mode): communicating unit 1=interrupted communicating unit 2=interrupted Operation procedures in the respective states are shown in the figures.
An example of a flowchart and a communication procedure at the time of startup of wireless power transmission in the normal mode of the wireless power transmission system according to the present embodiment is shown in
As the first procedure, the wireless power transmission system performs apparatus detection for searching for a power receiving apparatus (S1001). For the apparatus detection, the communicating unit 1 may be used or the communicating unit 2 may be used. An advantage of performing the apparatus detection using the communicating unit 1 is that, for example, it is possible to detect a target power receiving apparatus from a relatively wide range compared with the communicating unit 2. However, for the detection of a power receiving apparatus, it is necessary to always supply electric power to the communicating unit 1. Therefore, there is a disadvantage that consumed power increases. An advantage of performing the apparatus detection using the communicating unit 2 is that, for example, in particular, it is possible to reduce consumed power on a power receiving apparatus side. However, as explained above, the communicating unit 2 has an extremely narrow communicable range, there is a disadvantage that an apparatus detectable range is narrow. If a power receiving apparatus is found (Yes in S1002), the wireless power transmission system shifts to the next procedure. If a power receiving apparatus is not found (No in S1002), the wireless power transmission system repeats the apparatus detection. The apparatus detection may be always performed or may be cyclically performed. When the apparatus detection is cyclically performed, consumed power can be reduced compared with power consumed when the apparatus detection is always performed. Note that the apparatus detection may be performed by means other than the communicating unit 1 and the communicating unit 2. For example, a sensor, a camera, or a separate communication apparatus may be used. In
When a power receiving apparatus is detected by the apparatus detection, the wireless power transmission system performs authentication of the power receiving apparatus in order to determine whether the power receiving apparatus is a malicious apparatus having a purpose of a power theft or a obstacle (S1003). As the apparatus authentication, because of an advantage that a communicable range is limited when the communicating unit 2 is used, it is possible to perform authentication with high confidentiality. When the apparatus authentication is successful (Yes in S1004), the wireless power transmission system shifts to the next procedure. When the apparatus authentication is unsuccessful (No in S1004), the wireless power transmission system transitions to an error state. Rather than transitioning to the error state when the apparatus authentication is unsuccessful once, the wireless power transmission system may transition to the error state when the apparatus authentication is continuously unsuccessful a plurality of times. The wireless power transmission system may perform the apparatus authentication simultaneously with the apparatus detection or before the apparatus detection. In
When the apparatus authentication ends, the wireless power transmission system performs alignment (S1005). The alignment is a procedure for correcting a positional relation between the power transmitting apparatus and the power receiving apparatus for improving power transmission efficiency. When a power transmission characteristic acquired in the communicating unit 2 is used for the alignment, it is desirable to use the communicating unit 2. However, the alignment can be realized by the communicating unit 1 as well. The alignment could be sometimes unnecessary depending on an application to be applied. For example, when a setting position of the power receiving apparatus is explicitly marked in a power transmitting apparatus main body and a user arranges the power receiving apparatus in the setting position, communication is unnecessary and the user performs the alignment. The order of the alignment may be interchanged with the order of the apparatus detection and the apparatus authentication performed at the pre-stage of the alignment. When the alignment is successful, the wireless power transmission system shifts to the next procedure. When the alignment is unsuccessful, the wireless power transmission system transitions to the error state. Note that as a method of determining that the alignment is unsuccessful, it is possible to apply a method of setting time length from the start of the alignment as a threshold and determining that the alignment is unsuccessful if the alignment cannot be successfully performed for a fixed time or longer. Other determining methods may be used. There is also a method of performing the alignment using the communicating unit 1 or 2. A sensor, a camera, a separate communication apparatus, or the like may be used. Any method can be applied. When the alignment is performed, it is also possible to perform calibration necessary at the time of start of power transmission. In
When the alignment ends (yes in S1006), subsequently, as power transmission preparation, the wireless power transmission system exchanges pre-power transmission information and safety control information necessary at the time of start of power transmission (S1007). The information is transmitted using the communicating unit 1. In general, the communicating unit 1 has a higher transmission rate compared with the communicating unit 2. Therefore, when the communicating unit 1 is used, the wireless power transmission system can shift to the start of power transmission more quickly than when the communicating unit 2 is used.
When the exchange of the pre-power transmission information and the safety control information ends, the wireless power transmission system transmits a power transmission start notification (S1008) and starts power transmission (S1009). The wireless power transmission system may transmit the power transmission start notification using either of the communicating unit 1 or the communicating unit 2. The wireless power transmission system may start the power transmission without transmitting the power transmission start notification.
Note that for the position detection, the alignment, and the obstacle detection shown in
When coupling strength that enables power transmission is obvious, it is also possible to apply a method of setting the coupling strength as a threshold and aligning the position to set the coupling strength to be equal to or higher than the threshold.
A flowchart during power transmission and a communication procedure of wireless power transmission in the normal mode are shown in
During the wireless power transmission, the wireless power transmission system cyclically or suddenly performs a check of a transmission state, safety control, and radio communication for charging control to a battery (S2001). This is performed using the communicating unit 1. During power transmission, when communication is performed in the communicating unit 2 using, in particular, load modulation, deterioration in power transmission efficiency is caused. Therefore, it is desirable to use the communicating unit 1. When it is necessary to stop the power transmission (Yes in S2002) or some error occurs, the wireless power transmission system sends a power transmission stop notification (S2003) and stops the power transmission. Note that when communication timing, a data type, and a data cycle are exchanged beforehand, the wireless power transmission system may cyclically transmit information unilaterally from the power receiving apparatus without transmitting a request from the power transmitting apparatus shown in
A flowchart and a communication procedure at the time of startup of wireless power transmission in the interruption 1 mode of the wireless power transmission system according to the embodiment is shown in
In the interruption 1 mode, the control is executed up to the power transmission start according to the same procedures as the procedures in the normal mode. However, the interruption 1 mode is different from the normal mode in that all the kinds of information exchanged by the communicating unit 1. in the normal mode are exchanged by the communicating unit 2.
First, in apparatus detection (S3001), the method of detecting a power receiving apparatus using the communicating unit 2, a sensor, a camera, a separate communication apparatus, or the like may be used. Any method other than the detection by the communicating unit 1 can be applied. If a power receiving apparatus is found (Yes in S3002), the wireless power transmission system shifts to the next procedure. If a power receiving apparatus is not found (No in S3002), the wireless power transmission system repeats the apparatus detection.
Subsequently, the wireless power transmission system performs apparatus authentication (S3003) using the communicating unit 2 as in the normal mode. When the apparatus authentication is successful (Yes in S3004), the wireless power transmission system shifts to the next procedure. When the apparatus authentication is unsuccessful (No in S3004), the wireless power transmission system transitions to an error state. Note that rather than transitioning to the error state when the apparatus authentication is unsuccessful once, the wireless power transmission system may transition to the error state when the apparatus authentication is continuously unsuccessful a plurality of times. Note that the wireless power transmission system may perform the apparatus authentication simultaneously with the apparatus detection or before the apparatus detection.
When the apparatus authentication ends, the wireless power transmission system performs alignment (S3005). When a power transmission characteristic acquired in the communicating unit 2 is used for the alignment, it is desirable to use the communicating unit 2. However, any method of aligning a position using an apparatus other than the communicating unit 1 such as a sensor, a camera, or a communication apparatus can be applied. Note that the alignment could be sometimes unnecessary depending on an application to be applied. For example, when a setting position of the power receiving apparatus is explicitly marked in a power transmitting apparatus main body and a user arranges the power receiving apparatus in the setting position, communication is unnecessary and the user performs the alignment. The order of the alignment may be interchanged with the order of the apparatus detection and the apparatus authentication performed at the pre-stage of the alignment. It is also possible to perform, at the time of the alignment, calibration necessary at the time of power transmission start.
When the alignment ends (Yes in S3006), subsequently, for power transmission preparation, the wireless power transmission system exchanges pre-power transmission information and safety control information necessary at the time of start of power transmission (S3007). The information is transmitted using the communicating unit 2. At this point, information for notifying that the communicating unit 1 is interrupted and basic information for using the wireless power transmission and the inter-coil communication in common are exchanged in advance. Examples of the basic information include several items described below.
The communication timing is necessary to separate the wireless power transmission and the inter-coil communication, for example, when the wireless power transmission and the inter-coil communication are shared in a time-division manner.
In
The initial inter-coil communication can be carried out according to the communication timing. However, the inter-coil communication is cyclically carried out according to a data type and a data cycle exchanged in advance. The data cycle is sometimes different depending on the data type. In that case, a plurality of data types need to be mixed and transmitted. In
When a plurality of kinds of data types having different communication timings and data cycles are simultaneously transmitted, it is necessary to perform communication according to the data cycles of the respective data types as shown in
Note that the determination of communication timing and call timing is performed by the power transmission-side control unit 34 of the power transmitting apparatus. The power transmitting apparatus notifies the power receiving apparatus of the communication timing and the call timing determined by the power transmission-side control unit 34. The power receiving apparatus operates on the basis of information concerning the communication timing and the call timing.
Information concerning the data type and the data cycle is extremely important parameters in the interruption 1 mode. For example, the pre-power transmission information and the safety control information are included as types of data in the normal mode. In the interruption 1 mode, a data type is designated at the time of startup and only designated information is exchanged during power transmission. Consequently, it is possible to minimize resources used for communication and carry out power transmission control while minimizing deterioration in the power transmission efficiency. Note that as data types used in the interruption 1 mode, for example, electric power, electric current, and voltage information at respective measurement points, resistance information of a load or, when the load is a battery, charging information, and the like are included. However, the data types are not limited to such information. It is possible to improve the power transmission efficiency by saving information to be communicated as much as possible. Further, at this point, the data cycle is also exchanged. Basically, any control is performed according to a certain specific cycle and communication concerning the control is cyclically performed on the basis of the cycle. In particular, in the case of the wireless power transmission apparatus, the power transmitting apparatus requests necessary data and the power receiving apparatus returns data corresponding to the request. The exchange of the data is carried out at a fixed cycle. At this point, a cycle of data and a type of the data called from the power transmitting apparatus are exchanged before the start of power transmission. Consequently, it is possible to acquire data necessary for the control from the power receiving apparatus without performing a data request from the power transmitting apparatus. In other words, it is possible to realize transmission control for the wireless power transmission according to cyclic transmission of data in one-way from the power receiving apparatus. Consequently, it is possible to reduce resources necessary for communication and improve the power transmission efficiency.
When the exchange of the pre-power transmission information and the safety control information ends, the wireless power transmission system transmits a power transmission start notification (S3008) and starts power transmission (S3009). The wireless power transmission system also performs the power transmission start notification using the communicating unit 2. The wireless power transmission system may start the power transmission without transmitting the power transmission start notification.
Note that in
A flowchart and a communication procedure during power transmission of the wireless power transmission in the interruption 1 mode are shown in
An example of a procedure in the case of transitioning from another state to the interruption 1 mode during power transmission is shown in
A flowchart and a communication procedure at the time of startup of the wireless power transmission in the interruption 2 mode are shown in
As the first procedure, the wireless power transmission system performs apparatus detection for searching for a power receiving apparatus (S6001). For the apparatus detection, the communicating unit 1 may be used or a sensor, a camera, or a separate communication apparatus may be used. If a power receiving apparatus is found (Yes in S6002), the wireless power transmission system shifts to the next procedure. If a power receiving apparatus is not found (No in S6002), the wireless power transmission system repeats the apparatus detection. The apparatus detection may be always performed or may be cyclically performed. When the apparatus detection is cyclically performed, consumed power can be reduced compared with power consumed when the apparatus detection is always performed.
When a power receiving apparatus is detected by the apparatus detection, the wireless power transmission system performs authentication of the power receiving apparatus in order to determine whether the power receiving apparatus is a malicious apparatus having a purpose of a power theft or a obstacle (S6003). The apparatus authentication is performed using the communicating unit 1. When the communicating unit 2 is used, since the communicating unit 2 has a communicable range wider than a communicable range of the communicating unit 1, there are risks of wiretapping and piracy. Therefore, firm security measures may be taken according to necessity. Note that rather than transitioning to the error state when the apparatus authentication is unsuccessful once, the wireless power transmission system may transition to the error state when the apparatus authentication is continuously unsuccessful a plurality of times. The wireless power transmission system may perform the apparatus authentication simultaneously with the apparatus detection or before the apparatus detection.
Note that it can be determined whether the communicating unit 2 is interrupted only when communication is performed by the communicating unit 2 in the apparatus authentication unless the communicating unit 2 is used for the apparatus detection. Therefore, the wireless power transmission system transitions to the interruption 2 mode at the first stage of the use of the communicating unit 2.
When the apparatus authentication ends (Yes in S6004), the wireless power transmission system performs alignment (S6005). For the alignment, the communicating unit 1 may be used. Any method of aligning a position using an apparatus other than the communicating unit 2 such as a sensor, a camera, or a separate communication apparatus can be applied. Note that the alignment could be sometimes unnecessary depending on an application to be applied. For example, when a setting position of the power receiving apparatus is explicitly marked in a power transmitting apparatus main body and a user arranges the power receiving apparatus in the setting position, communication is unnecessary and the user performs the alignment. When the alignment is performed, it is also possible to perform calibration necessary at the time of start of power transmission.
When the alignment ends (Yes in S6006), subsequently, the wireless power transmission system exchanges pre-power transmission information and safety control information necessary at the time of start of power transmission (S6007). The information is transmitted using the communicating unit 1. At this point, in the interruption 2 mode, information for notifying the power receiving apparatus that the communicating unit 2 is interrupted may be added.
When the exchange of the pre-power transmission information and the safety control information ends, the wireless power transmission system transmits a power transmission start notification using the communicating unit 1 (S6008) and starts power transmission (S6009). The wireless power transmission system may start the power transmission without transmitting the power transmission start notification.
A flowchart and a communication procedure during power transmission of the wireless power transmission in the interruption 2 mode are shown in
Note that, in the interruption 2 mode, it is possible to omit the power transmission information and safety control information request from the power transmitting apparatus at the time of power control as in the interruption 1 mode. However, a power transmission efficiency improving effect as in the interruption 1 mode is not obtained.
When both of the communicating unit 1 and the communicating unit 2 are interrupted, the wireless power transmission system transitions to the full interruption mode. In this full interruption mode, irrespective of whether the power transmission is started up or being performed, the wireless power transmission system determines that the wireless power transmission system is in a power transmission impossible state (S8001) and does not perform the wireless power transmission. In this mode, the control unit repeatedly performs a check of communication restoration in both of the communicating unit 1 and the communicating unit 2 (S8002, S8003, and S8004). When any one of or both of the communicating unit 1 and the communicating unit 2 are restored, the wireless power transmission system transitions to the respective modes and performs startup processing or power transmission.
In the wireless power transmission system according to the embodiment, in a state in which power transmission needs to be immediately emergently stopped because of heat generation of the power receiving apparatus, breakage of an apparatus, overvoltage, overcurrent, or the like, it is necessary to perform radio communication in order to notify that the power transmission is emergently stopped. At this point, when the emergency stop of the power supply is notified using the communicating unit 1 in which a general communication standard such as wireless LAN or Bluetooth is used, since a delay is caused by processing in respective protocols or processing by an access control unit such as a MAC layer, it is extremely difficult to satisfy a delay time allowed until the emergency stop. Therefore, in this proposal, when the emergency stop is immediately necessary, an emergency stop signal is exchanged using the communicating unit 2 in both the normal mode and the interruption 1 mode unless the communicating unit 2 is interrupted. When the communicating unit 2 is used, it is easy to change the configuration of a frame. For example, if a preamble for emergency stop including a code different from a preamble part usually used in the communicating unit 2 is used as a preamble part of a frame as shown in
Rather than using the preamble for emergency stop, the protection circuit 42 included in the power receiving apparatus in a wireless power transmission system shown in
Note that changes in a voltage and an electric current on the power transmitting apparatus side at the time of the protection circuit operation are different depending on circuit topologies. Therefore, it is necessary to select an optimum method for determining the protection circuit operation according to each of the topologies. Note that examples of a place where the voltage and electric current changes are measured on the power transmitting apparatus side of the protection circuit operation in this case include a place between the power transmission antenna and the inverter, a place between the power distributing unit and the inverter, and a place between the power supply unit and the inverter. However, besides these places, the place for measuring the voltage and electric current changes may be any place where the protection circuit operation is read in the power transmitting apparatus.
A second configuration example of the wireless power transmission system according to the embodiment is shown in
A second operation example and a flowchart in the respective mode in the wireless power transmission system according to the present embodiments are substantially the same as the first operation example. The second operation example and the flowchart are different from those in the first operation example in that all kinds of control and start of communication are performed in the power reception-side control unit 44 of the power receiving apparatus, which is the master. That is, arrows of the communication procedures in the figures are only opposite. Therefore, explanation of the second operation example and the flowchart is omitted.
The embodiments can be widely applied to wireless power transmission techniques and can be applied to a wireless communication device as a highly reliable technique concerning wireless communication.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
This application is a Continuation of International Application No. PCT/JP2013/074171, filed on Sep. 3, 2013, the entire contents of which is hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2013/074171 | Sep 2013 | US |
| Child | 14175464 | US |
