Power transmitting apparatus, method of controlling the same, and power transmission system
8 claims: 6 independent, 2 dependent
- 1受電装置であって、送電装置から無線で電力を受電する受電手段と、送電装置と 、負荷変調により 通信を行う第1通信手段と、 送 電装置と 、Bluetooth(登録商標)の規格に準拠する 通信を行う第2通信手段と、を有し、前記第2通信手段は、前記受電装置 のアドレス 情報を含む第1信号を送信し、前記第1通信手段は、前記第1信号に含まれる前記 アドレス 情報を含む第2信号を送信し、前記第2通信手段は、前記 アドレス 情報を含む前記第1信号と前記 アドレス 情報を含む前記第2信号とを受信した送電装置から 、第 3信号を受信することを特徴とする受電装置。
- 2前記第2通信手段は、前記送電装置と、受電する電力に係る受電パラメータに関する通信を行うことを特徴とする請求項1に記載の受電装置。
- 3前記受電パラメータは、前記受電装置が要求する電力を含むことを特徴とする請求項2に記載の受電装置。
- 4前記第3信号は、乱数を含むことを特徴とする請求項1乃至 3 のいずれか1項に記載の受電装置。
- 5前記乱数は、前記 アドレス 情報を含む前記第1信号と、前記 アドレス 情報を含む前記第2信号とを受信した前記送電装置により生成された乱数であることを請求項 4 に記載の受電装置。
- 6受電装置の制御方法であって、前記受電装置は、送電装置から無線で電力を受電する受電手段と、送電装置と 、負荷変調により 通信を行う第1通信手段と、 送 電装置と 、Bluetooth(登録商標)の規格に準拠する 通信を行う第2通信手段と、を有し、前記制御方法は、前記第2通信手段が、前記受電装置 のアドレス 情報を含む第1信号を送信する工程と、前記第1通信手段が、前記第1信号に含まれる前記 アドレス 情報を含む第2信号を送信する工程と、前記第2通信手段が、前記 アドレス 情報を含む前記第1信号と前記 アドレス 情報を含む前記第2信号とを受信した送電装置から 、第 3信号を受信する工程と、を含むことを特徴とする制御方法。
- 7前記第3信号は、乱数を含むことを特徴とする請求項 6 に記載の制御方法。
- 8請求項 6又は7 に記載の制御方法をコンピュータに実行させるためのプログラム。
Independent claims8
143 paragraphs, as filed
The present invention relates to wireless power transmission technology.
In recent years, technological development of wireless power transmission systems has been widely carried out. By the way, when a foreign object such as a metal piece is present within the power transmission range of the power transmission device, an eddy current flows within the foreign object, causing unintended heat generation. Therefore, in a wireless power transmission system, it is necessary to appropriately transmit power to a power receiving device while taking into consideration the influence on foreign objects. For example, Patent Document 1 proposes a technique in which a power receiving device is provided with a Q value measuring circuit for a power transmitting antenna, and foreign objects are detected based on the results of measuring the Q value.
<p><patcit num="1"><text>Japanese Patent Application Publication No. 2013-17379</text></patcit></p>
<p>The present invention<u style="Single">Receive power properly from power transmission equipment</u>The purpose is to provide technology.</p>
<p>In order to solve the above problems, a power receiving device according to the present invention has the following configuration. In other words, the power receiving device includes a power receiving means that wirelessly receives power from the power transmitting device, and a power receiving device that receives power wirelessly from the power transmitting device.<u style="Single">, due to load modulation</u>a first communication means for communicating;<u style="Single"> Sending</u>electrical equipment and<u style="Single">, Compliant with Bluetooth (registered trademark) standards</u>a second communication means for communicating, and the second communication means communicates with the power receiving device.<u style="Single">address of</u>transmitting a first signal including information, the first communication means transmitting the information included in the first signal;<u style="Single">address</u>transmitting a second signal containing information, the second communication means transmitting a second signal containing information;<u style="Single">address</u>said first signal containing information and said<u style="Single">address</u>from the power transmission device that received the second signal containing the information.<u style="Single">, No.</u>3 Receive signal.</p>
<p>According to the invention,<u style="Single">Receive power properly from power transmission equipment</u>technology can be provided.</p>
<figref num="1">FIG. 1 is an overall configuration diagram of a power transmission system according to a first embodiment.</figref><figref num="2">FIG. 2 is a diagram exemplarily showing a state around a power transmission range in a power transmission system.</figref><figref num="3">5 is a diagram illustrating the operation of the detection unit 103. FIG.</figref><figref num="4">FIG. 2 is a diagram exemplarily showing the configuration of a class E amplifier.</figref><figref num="5">5 is a timing diagram illustrating operations of power transmitting section 113 and detecting section 103. FIG.</figref><figref num="6">FIG. 3 is a timing diagram illustrating the operation of the power transmission device.</figref><figref num="7">3 is a diagram exemplarily showing flags stored in a system state storage unit 105. FIG.</figref><figref num="8">3 is a diagram exemplarily showing information stored in an ID storage unit 106 of a power transmission device. FIG.</figref><figref num="9">3 is a diagram exemplarily showing information stored in an ID storage unit 121 of a power receiving device. FIG.</figref><figref num="10">5 is an operation flowchart of the detection unit 103.</figref><figref num="11">3 is an operational flowchart of BT control in power transmission device 100.</figref><figref num="12">3 is an operational flowchart of power transmission control in the power transmission device 100.</figref><figref num="13">3 is an operational flowchart of BT control in the power receiving device 101. FIG.</figref><figref num="14">3 is an operation flowchart of power reception control in the power reception device 101. FIG.</figref><figref num="15">5 is a diagram exemplarily showing information stored in an impedance storage unit 110. FIG.</figref>
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Note that the following embodiments are merely illustrative, and are not intended to limit the scope of the present invention.
(First Embodiment) As a first embodiment of the power transmission system according to the present invention, a wireless power transmission system including a power transmission device 100 and a power reception device 101 that perform wireless power transmission will be described below as an example.
<Device Configuration> FIG. 1 is an overall configuration diagram of the power transmission system according to the first embodiment. Power transmitting device 100 and power receiving device 101 perform power transmission via medium 102. Note that, as will be described in detail below, the power transmitting device and the power receiving device exchange control information used for controlling wireless power transmission via communication units included in each device. Therefore, control for establishing and disconnecting the communication path between the power transmitting device and the power receiving device will also be described.
First, the configuration of power transmission device 100 will be explained. The detection unit 103 is a functional unit that detects the output impedance value of the DC voltage source 401 of the class E amplifier that constitutes the power transmission unit 113 (hereinafter referred to as Z detection), and the details will be described later. Control unit 104 is a functional unit that controls power transmission device 100 according to the detection result of detection unit 103. The system status storage unit 105 is a functional unit that stores the status of the power transmission system, and details will be described later with reference to FIG. 7. ID storage unit 106 is a functional unit that stores identification information of power receiving device 101, and details will be described later with reference to FIG. 8.
The first timer 107, the second timer 108, and the third timer 109 are timers that can be used depending on the operating state of the system, and details will be described later. The impedance storage unit 110 is a functional unit that stores the detection result of the impedance value by the detection unit 103, and the details will be described later with reference to FIG. 15. The error release switch 111 is a functional unit that accepts, for example, an operation from a user in order to release the error state of the system. The display unit 112 is a functional unit that displays information regarding the wireless power transfer system, and displays error information, for example.
Power transmission unit 113 supplies power transmitted via medium 102 to power transmission antenna 115. Here, power transmission section 113 will be explained as being configured with a class E amplifier. Resonance control unit 114 is a functional unit that controls the resonance frequency and characteristic impedance of the transmission path configured by power transmission antenna 115, power reception antenna 125, and medium 102.
The communication unit 116 (power transmitting device side communication means) is a functional unit that transmits and receives a control signal related to the power transmitted between the power transmitting antenna 115 and the power receiving antenna 125. Note that the control signal is transmitted and received via a communication antenna (not shown). In the first embodiment, the communication unit 116 is compatible with the Bluetooth (registered trademark) standard (hereinafter referred to as BT), but may be compatible with other communication standards. Furthermore, here, the communication unit 116 functions as a master device of the BT standard. Further, as will be described in detail later, the power transmission device 100 is configured to use SDP (Service Discovery Protocol) to announce the services it provides to surrounding devices. Here, we will announce that we provide a service called Wireless Charger.
Next, the configuration of power receiving device 101 will be explained. Power receiving unit 117 is a functional unit that receives power transmitted from an external device (here, power transmitting device 100). The load 118 consumes the power received by the power receiving unit 117, and here it is composed of a charging circuit and a battery. The communication unit 119 (power receiving device side communication means) is a functional unit that transmits and receives a control signal related to the power transmitted between the power transmitting antenna 115 and the power receiving antenna 125. Like the communication section 116, it complies with the BT standard. Here, the communication section 119 will be explained as functioning as a slave device according to the BT standard.
Comparison unit 120 is a functional unit that compares information received by power receiving antenna 125 and information received by communication unit 119. ID storage unit 121 stores information received by power reception antenna 125 and identification information of power transmission device 100 received by communication unit 119. The fourth timer 122 and the fifth timer 123 are timers that can be used depending on the operating state of the system, and details will be described later.
The display unit 124 is a functional unit that displays information regarding the wireless power transfer system, and displays error information, for example. Power receiving antenna 125 is a functional unit that is electromagnetically coupled to power transmitting antenna 115 and receives power. Switching unit 125 is a functional unit that connects power receiving antenna 125 to resonance unit 128 or high resistance 127.
The high resistance 127 is, for example, a constant resistance of about several megaohms. By connecting power receiving antenna 125 and constant resistor 117, the impedance of power receiving antenna 125 viewed from power transmitting antenna 115 is configured to be high impedance (hereinafter referred to as Hi-Z). Note that by setting it to Hi-Z, the current flowing through the power receiving antenna 125 becomes almost zero.
The resonant unit 128 is a functional unit that causes the power transmission path to resonate with a specific impedance. Here, the power transmission path is composed of the resonance control section 114, the power transmission antenna 115, the medium 102 serving as the transmission path, and the power reception antenna 125. Note that the characteristic impedance 129 is the characteristic impedance when the resonant circuit is viewed from the load switching unit 130, and here the value is assumed to be Zo.
The load switching unit 130 is a functional unit that switches between the matching resistor 132, the load control unit 133, and the intermediate resistor 131 whose resistance value is approximately equal to Zo. The medium resistance 131 has a lower resistance value than the high resistance 127 and a higher resistance value compared to the matching resistance 122. The medium resistance 131 is for making the impedance of the power receiving antenna 125 seen from the power transmitting antenna 115 medium impedance (hereinafter referred to as Md-Z) by connecting the load switching unit 130. By setting the impedance of the power receiving antenna 125 seen from the power transmitting antenna 115 to Md-Z, a minute current flows through the power receiving antenna 125 and the medium resistance 131.
The load control unit 133 is an impedance conversion circuit that performs an operation to match the load impedance that changes depending on the power consumption of the load 118 with the characteristic impedance 119 (Zo), and is configured with a DC-DC converter or the like. Note that the load impedance means the impedance of the load 118 viewed from the load control unit 133.
Note that hereinafter, the operation of impedance conversion will be referred to as load impedance control. Load control section 133 and matching resistor 132 have the same function in that they perform impedance matching with resonant section 128. However, since the load control unit 133 performs impedance conversion after detecting a change in the impedance of the load 118, it takes a certain amount of time until the operation becomes stable. On the other hand, since the matching resistor 132 is a constant resistor, it does not take time for the operation to stabilize.
<Impedance in the vicinity of the power transmission range> FIG. 2 is a diagram illustrating the state around the power transmission range in the power transmission system. Note that the communication range 200 indicates a range in which communication by the communication unit 116 of the power transmission device 100 is possible. Power transmission range 201 indicates the range in which power transmission antenna 115 can transmit power. As shown in FIG. 2, the communication range 200 is wider than the power transmission range 201, and the communication range 200 is configured to include the entire power transmission range 201.
FIG. 2(a) shows a state in which nothing is placed in the power transmission range 201. That is, neither the power receiving device 101 nor the foreign object 202 exists in the power transmission range 201. FIG. 2(b) shows a state in which only a foreign object 202 exists in the power transmission range 201. FIG. 2(c) shows a state where only the power receiving device 101 exists in the power transmission range 201. However, in FIG. 2(c), the power transmitting device 100 does not transmit power to the power receiving device 101. 2(d) is the same as FIG. 2(b) in that the power receiving device 101 is present in the power transmission range 201, but the power transmitting device 100 is transmitting power to the power receiving device 101. Note that the arrow 202 conceptually indicates that power is being transmitted.
The power transmission device 100 needs to be controlled not to transmit power when the object present in the power transmission range 201 is a foreign object 202 (FIG. 2(b)). On the other hand, when the object present in the power transmission range 201 is the power reception device 101 (FIG. 2(c)), the power transmission device 100 needs to be controlled to transmit power.
FIG. 3 is a diagram illustrating the operation of the detection unit 103. FIG. 3 is composed of a power transmitting antenna 115, a power receiving antenna 125, and a foreign object 202. Voltage V1 indicates the voltage across power transmission antenna 115. Current I1 indicates the current flowing through the power receiving antenna 125, and current I2 indicates the current flowing through the foreign object 202. Z is the impedance value of the power receiving antenna 125.
The value of voltage V1 changes depending on current I1 and current I2. Therefore, the voltage V1 (referred to as V_init here) when there is no foreign object 202 and power receiving device 101 in the power transmission range 201 as shown in FIG. Indicates a value different from the state voltage V1. In other words, if the power transmitting device 100 stores the voltage V_init in advance when there is no foreign object 202 and the power receiving device 101 in the power transmission range 201, it can detect the voltage V1 in the state shown in FIG. 2(b) and compare it with V_init. , the foreign object 202 can be detected. Furthermore, when the power receiving device 101 is present in the power transmission range 201 as shown in FIG. 2(c), the voltage V1 similarly shows a different value from V_init. That is, the power transmitting device 100 can detect that the foreign object 202 or the power receiving device 101 is within the power transmission range 201 by comparing V_init and the voltage V1.
By the way, the magnitude of the current I1 flowing through the power receiving antenna 125 can be controlled by changing the impedance Z. If the impedance Z is set to Hi-Z (for example, infinite), the current I1 becomes zero. When the power receiving device 101 is located in the power transmission range 201 as shown in FIG. 2(c), the voltage V1 shows a value different from V_init as described above. In this state, if the power receiving device 101 controls the impedance Z to Hi-Z, that is, the current I1 becomes zero, the voltage V1 becomes equal to V_init.
In the state of FIG. 2(c), power transmitting device 100 can detect the presence of foreign object 202 or power receiving device 101 in power transmitting range 201 based on a change in voltage V1. However, the power transmitting device 100 cannot determine whether the change factor is the foreign object 202 or the power receiving device 101.
By the way, in the state of FIG. 2(c), if the impedance Z is controlled so that the power receiving device 101 becomes Hi-Z, the current I1 becomes zero and the voltage V1 becomes V_init. In other words, the power transmitting device 100 can determine that the power receiving device 101 exists within the power transmitting range 201. On the other hand, if power receiving device 101 controls impedance Z to be Hi-Z and voltage V1 is not equal to V_init, power transmitting device 100 can detect that foreign object 202 is present in power transmission range 201.
Furthermore, in the state of FIG. 2(c), if the impedance Z of the power receiving device 101 is controlled so that it becomes Md-Z, a small current flows through the power receiving antenna 125 and the impedance Z. Therefore, power receiving device 101 can detect power transmitting device 100 by detecting a minute current. Note that the change in voltage V1 also appears in the change in the input impedance of power transmission antenna 115, which is obtained by dividing voltage V1 by the current flowing through power transmission antenna 115.
FIG. 4 is a diagram illustrating a configuration of a class E amplifier that constitutes power transmission section 113. The class E amplifier consists of an N-channel MOSFET 405, two inductors, and two capacitors. 403 is a gate terminal, 402 is a drain terminal, and 404 is a source terminal. 401 is a DC voltage source input to the N-channel MOSFET 405. Power transmission section 113 is connected to power transmission antenna 115 via resonance control section 114. Therefore, the input impedance of the power transmission antenna 115 appears as a change in the output impedance of the class E amplifier. Further, a change in the output impedance of the class E amplifier appears as a change in the output impedance of the DC voltage source 401.
That is, the power transmitting device 100 can detect the foreign object 202 or the power receiving device 101 by storing in advance the output impedance value of the DC voltage source in the state shown in FIG. 2(a). Below, the output impedance value (initial impedance value) of the DC voltage source in the state of FIG. 2(a) will be expressed as Z_init.
Next, three impedance values (Hi-Z, Md-Z, Zo) set as the impedance of power receiving device 101 will be explained.
Hi-Z is an impedance value used for device protection and device detection. If a large current suddenly flows through the power receiving circuit 117 including the power receiving antenna 125, there is a risk that the circuit will be destroyed, which is very dangerous from the viewpoint of circuit protection. Therefore, by setting the impedance of the power receiving device 101 to Hi-Z, the current I1 flowing through the power receiving circuit 117 can be reduced to zero in principle, and the risk can be reduced. Therefore, from the viewpoint of circuit protection, the power receiving device 101 is made to be Hi-Z as much as possible. Further, as described above, although the power transmitting device 100 can detect that at least one of the foreign object 202 and the power receiving device 101 is present in the power transmission range 201 by detecting a change in the voltage V1, it cannot determine which one is present. At this time, by setting the impedance of power receiving device 101 to Hi-Z, discrimination by power transmitting device 100 is enabled.
Md-Z is an impedance value used for device detection. As described above, the power receiving device 101 can detect the power transmitting device 100 by setting the impedance to Md-Z. Further, since the voltage V1 of the power transmitting antenna 115 changes due to the minute current flowing through the power receiving antenna 125, the power transmitting device 100 can also detect the power receiving device 101 if the impedance of the power receiving device 101 is set to Md-Z.
Zo is an impedance value used when calculating transmission efficiency. The transmission efficiency between the power transmitting antenna 115 and the power receiving antenna 125 decreases due to reflection when the output impedance of the power transmitting antenna (output impedance Z in FIG. 3) and the impedance of the load are not matched. Therefore, it is better for the power transmitting device 100 to calculate the transmission efficiency between the power transmitting and receiving antennas before starting power transmission to the power receiving device 101, and not transmit power if the efficiency is too low. When calculating transmission efficiency, in the case of Hi-Z and Md-Z, impedance matching between the power receiving antenna and the load cannot be achieved and reflections are large, so it is not possible to accurately calculate the transmission efficiency between the power transmitting and receiving antennas. Therefore, when calculating the transmission efficiency, the impedance of the power receiving device 101 is set to Zo so that it matches the output impedance Zo of the power receiving antenna. Naturally, in order to improve transmission efficiency, the impedance of the power receiving device 101 is set to Zo when receiving power from the power transmitting device 100.
<Operation of the detection unit of the power transmission device> FIG. 5 is a timing diagram illustrating the operation of the power transmission unit 113 and the detection unit 103. The horizontal axis is time. The power transmitting unit 113 transmits a detection signal 502 for the detecting unit 103 to perform Z detection via the power transmitting antenna 115 from time T1 to time T2. Further, from time T2 to time T3, a BT address, which is an address uniquely assigned to communication unit 116, is transmitted as a BT address signal 503 via power transmission antenna 115.
Detection unit 103 detects the impedance of DC voltage source 401 from time T1 to time T3. A square 504 indicates that the detection unit 103 is performing Z detection. Furthermore, the height of the square 504 conceptually indicates the magnitude of the Z-detected impedance. For example, in the case of FIG. 2(a), the height of square 504 corresponds to Z_init. In the following description, the sum 506 of the detection signal 502 and the BT address signal 503 will be expressed as a "pulse" in the following description.
<Information Stored in Various Storage Units> FIG. 7 is a diagram illustrating flags stored in the system status storage unit 105.
The power transmission flag 700 is a flag that is set to "1" when the power transmission device 100 starts transmitting power, and is set to "0" when the power transmission device 100 stops transmitting power. The hold flag 701 is a flag that is set to "1" when power transmission is stopped while the control unit 104 makes a determination, and is set to "0" otherwise. The prohibition flag 703 is a flag that is set to "1" when power transmission is prohibited, and is set to "0" otherwise. The device flag 704 is set to "1" when a BT connection is made between the communication unit 116 of the power transmission device 100 and the communication unit 119 of the power reception device 101, and is set to "0" otherwise. It's a flag.
FIG. 8 is a diagram illustrating information stored in the ID storage unit 106 of the power transmission device. After the control unit 104 determines that the cause of the impedance change is the power receiving device 101, the BT address of the power receiving device 101 is stored in the storage area 800. Further, when the control unit 104 disconnects the BT connection with the power receiving device 101, the BT address of the corresponding power receiving device 101 is cleared from the storage area 800.
FIG. 9 is a diagram illustrating information stored in the ID storage unit 121 of the power receiving device. When the power receiving antenna 125 receives the pulse 506 that the power transmitting unit 113 transmits via the power transmitting antenna 115 and detects the BT address included in the pulse 506, the detected BT address is stored in the storage area 900. Further, when the power transmitting device 100 stops power transmission, that is, when the hold flag or the prohibition flag is "1", the power receiving device 101 erases the BT address stored in the storage area 900.
On the other hand, the BT address stored in the storage area 901 is the BT address of the power transmitting device 100 received by the communication unit 119 of the power receiving device 101 via the communication unit 116 of the power transmitting device 100. When the power transmitting device 100 transmits an Inquiry message, which will be described later, and the power receiving device 101 receives the Inquiry message, the power receiving device 101 detects the BT address of the power transmitting device that is the transmission source from the header information of the Inquiry message. Then, the detected BT address is stored in the storage area 901. Further, when the BT connection between the power transmitting device 100 and the power receiving device 101 is disconnected, the power receiving device 101 erases the BT address stored in the storage area 901.
FIG. 15 is a diagram exemplarily showing information stored in impedance storage section 110. In Z_now of column 1501, the impedance value obtained as a result of Z detection by detection unit 103 is stored (overwritten). Note that, prior to overwriting, the detection unit 103 copies the contents of Z_now to Z_before in column 1500. By doing this, the impedance value in the previous Z detection is stored in Z_before, and it becomes possible to compare it with Z_now, which is the result of the latest Z detection.
<Operation example 1 of power transmission system (operation when there is a foreign object)> FIG. 6 is a timing diagram illustrating the operation of the power transmission device. In particular, FIG. 6(a) is a timing diagram of the power transmission device 100 when the foreign object 202 enters the power transmission range 201 at time Ta4, and the horizontal axis is time. Further, FIG. 10 is an operation flowchart of the detection unit 103.
First, the operation of the power transmission device 100 in the state shown in FIG. 2(a), that is, in the initial state where nothing is arranged, will be described. In the state shown in FIG. 2(a), the system state storage unit 105 is in a state where the flag shown in line 705 is stored. According to line 705, power transmission device 100 is not transmitting power, and power transmission flag 700 is "0" (YES in S1000).
Therefore, the detection unit 103 updates Z_before to Z_init. Then, the first timer 107 is reset at time Ta1 (S1002). When the first timer 107 times out at time Ta2 (YES in S1003), the detection unit 103 transmits the pulse 506 until time Ta3 (S1004). Then, the detection unit 103 performs Z detection from time Ta2 to Ta3 (S1005).
A square 602 indicates that the detection unit 103 performs Z detection from time Ta2 to Ta3, and the height of the square 602 conceptually indicates the magnitude of the impedance detected at this time. According to FIG. 6(a), the height of square 602 is equal to Z_init. Therefore, the detection unit 103 stores Z_init in Z_now (S1006).
The information stored in impedance storage section 110 at this time is shown in row 1502. In line 1502, Z_before and Z_now are both Z_init and are equal (YES in S1011). Also, according to line 705, the power transmission flag 700 is "0" (NO in S1012), the prohibition flag 703 is "0" (NO in S1013), and the device flag 704 is also "0" (NO in S1016). . Therefore, the detection unit 103 resets the first timer 107 again at time Ta3.
Suppose that the foreign object 202 enters the power transmission range 201 at time Ta4. That is, assume that at time Ta4 the state shifts to the state shown in FIG. 2(b). A square 604 indicates that the foreign object 202 is present in the power transmission range 201 from time Ta4 to time Ta7.
The detection unit 103 performs Z detection from Ta5 to Ta6. Note that the first timer 107 is set so that Z detection times out at Ta6. The impedance detected at this time is shown in a square 603. The height of the square 603 conceptually indicates the magnitude of the impedance detected at this time, and is assumed to be Z1 here. According to FIG. 6(a), the height Z1 of the square 602 is not equal to Z_init.
The information stored in impedance storage section 110 at this time is shown in row 1503. In line 1503, Z_now and Z_before are not equal (NO in S1011). Therefore, the detection unit 103 determines that the foreign object 202 or the power receiving device 101 is present in the power transmission range 201 (S1018).
The flags stored in the system state storage unit 105 at this time are as shown in line 705, and the power transmission flag 700 is "0" (NO in S1019). Subsequently, the detection unit 103 updates the suspension flag 701 to "1" (S1020). Line 706 shows the system state storage unit 105 at this time. According to line 706, the suspension flag 701 is "1", which means that the control unit 104 must determine whether the impedance change is caused by the foreign object 202 or the power receiving device 101. In order to make this determination, the detection unit 103 activates the control unit 104 and proceeds to S1100 (FIG. 11).
FIG. 11 is an operational flowchart of BT control in power transmission device 100. Here, the state is shown in FIG. 2(b), and the power receiving device 101 is not present. Therefore, the BT (communication unit 119) of the power transmission device 100 is not activated (NO in S1100). Therefore, the control unit 104 activates BT as a master (S1101), and transmits an inquiry message from the communication unit 119 to inquire about peripheral BT compatible devices according to the BT standard (S1102, 605).
Here, if the power receiving device 101 exists, an Inquiry response message (response signal) that is a response to the Inquiry message is sent back. However, since the foreign object 202 does not respond to the Inquiry message, the control unit 104 does not receive the Inquiry response message (NO in S1103). Therefore, the control unit 104 determines that the cause of the impedance change detected from time Ta5 to Ta6 does not correspond to BT (S1127) and is the foreign object 202 (S1120). At the same time, the suspension flag 701 is updated to "0" and the prohibition flag 703 is updated to "1" (S1121, S1122).
Then, the control unit 104 displays an error on the display unit 112 to notify the user that the foreign object 202 exists in the power transmission range 201 or that power transmission is prohibited (S1123). The flags stored in the system state storage unit 105 at this time are as shown in line 707. Since the foreign object 202 exists in the power transmission range 201, the prohibition flag 703 is "1". According to line 707, there is no BT connection with power receiving device 101, and device flag 704 is "0" (NO in S1124). Therefore, the control unit 104 operates the detection unit 103 to confirm that the foreign object 202 has been removed from the power transmission range 201 (S1126), and returns to S1000 (S1129). Here, at Ta7, for example, suppose that the user sees the error display and removes the foreign object 202 from the power transmission range 201.
From time Ta8 to Ta9, the detection unit 103 transmits a pulse and performs Z detection. Since the foreign object 202 has been removed from the power transmission range 201, the state between Ta8 and Ta9 is as shown in FIG. 2(a), and the impedance storage unit 110 is as shown in row 1502. According to line 707, since the prohibition flag 703 is "1" (YES in S1013), the detection unit 103 determines that the foreign object 202 has been removed (S1017), updates the prohibition flag 703 to "0", and then Turn off the error display (S1015). Then, the detection unit 103 returns to the process of S1000.
As described above, the detection unit 103 stores as Z_init the output impedance of the DC voltage source of the class E amplifier when a pulse is transmitted in a state where both the foreign object 202 and the power receiving device are not present in the power transmission range 201. Then, pulses were periodically transmitted via the power transmission antenna, and the output impedance at that time was compared with the stored Z_init. Thereby, the power transmitting device 100 can recognize that at least one of the foreign object 202 and the power receiving device 101 is present in the power transmitting range 201 by detecting a change in impedance. In addition, the power transmitting device 100 can recognize that it is a foreign object 202 by confirming that there is no response to the Inquiry message.
Note that in the above description, the detection unit 103 is configured to detect the output impedance of the DC voltage source 401, but it also detects other physical quantities that change due to electromagnetic coupling between the power transmission antenna 115 and the foreign object 202. It may be configured as follows. For example, the configuration may be such that the voltage V1 of the power transmission antenna 115 is detected. Further, the power transmission device 100 causes the communication unit 116 to operate as a BT master, and transmits an inquiry message in 605. Therefore, foreign objects that do not respond to inquiry messages can be identified at an early stage. The Inquiry message may be any other packet that expects a response from the power receiving device 101. Further, the communication unit 116 may be configured to use a communication standard other than BT (for example, wireless LAN).
<Operation example 2 of power transmission system (operation when there is a power receiving device)> FIG. 6 is a timing diagram illustrating the operation of the power transmitting device. In particular, FIG. 6(b) is a timing diagram of the power transmitting device 100 and the power receiving device 101 when the power receiving device 101 is present in the power transmission range 201. Note that the horizontal axis conceptually represents time, and the vertical axis conceptually represents the impedance of power receiving device 101 as seen from power transmitting antenna 115.
Furthermore, Hi-Z, Md-Z, and Zo (Hi-Z>Md-Z>Zo) are shown as three predetermined impedance values. The control of the power receiving device 101 to set each impedance is as described above. A square 610 indicates that the impedance of the power receiving device 101 is Hi-Z from time Tb1 to Tb2. A square 611 indicates that the impedance of the power receiving device 101 is Md-Z from time Tb2 to Tb3. A square 615 indicates that the impedance of the power receiving device 101 is Zo from time Tb5 to Tb6.
Furthermore, a square 612 indicates that the detection unit 103 transmits the pulse 506 and performs Z detection during the period from time Tb2 to Tb3, and the Z detection result is a dotted line 624. As is clear from comparing the dotted line 624 and Z_init, the impedance detected by the detection unit 103 between time Tb2 and Tb3 is not equal to Z_init.
FIG. 13 is an operation flowchart of BT control in power receiving device 101. If the remaining battery level is less than a predetermined threshold (for example, 95%) (YES in S1300), the power receiving device 101 starts the fourth timer 122 at time Tb1 (S1302) and sets the power receiving device 101 to Hi-Z. (S1303).
When the fourth timer 122 times out at time Tb2 (S1304), the power receiving device 101 starts the fifth timer 123 (S1305) and connects the switching unit 126 to the resonance unit 128 (S1306). Then, the power receiving device 101 connects the load switching unit 130 to the medium resistance 131, and sets the power receiving device 101 to Md-Z (S1307).
Here, the functions of the fourth timer 122 and the fifth timer 123 will be explained. The fourth timer 122 defines the time when the power receiving device 101 is in Hi-Z, and the fifth timer 123 defines the time when the power receiving device 101 is in Md-Z. That is, unless the power receiving device 101 receives the pulse 506 from the power transmitting device 100 (NO in S1308, which will be described later), the power receiving device 101 repeats the state change from Hi-Z to Md-Z.
The detection unit 103 detects an impedance different from Z_init from time Tb2 to Tb3. Therefore, the detection unit 103 knows that the foreign object 202 or the power receiving device 101 is present in the power transmission range 201.
Here, since the power receiving device 101 has an impedance of Md-Z, a small current flows through the medium resistance 131 due to the pulse 506 (that is, the detection signal 502 and the BT address signal 503) transmitted by the power transmitting unit 113 from Tb2 to Tb3. . Therefore, by detecting the voltage generated across the medium resistance 131, the power receiving device 101 can obtain the BT address of the power transmitting device 100 included in the BT address signal 503. At this point, the power receiving device 101 can recognize that it exists within the power transmission range 201 of the power transmitting device 100.
When the power receiving device 101 receives the pulse 506 (control signal) (YES in S1308), the impedance of the power receiving device 101 changes at time Tb3, regardless of whether or not the fifth timer 123 times out, from the viewpoint of circuit protection described above. to Hi-Z immediately (S1310).
Then, the power receiving device 101 stores (updates) the BT address of the power transmitting device 100 acquired in S1311 in the storage area 900 of the ID storage unit 121 (S1312). Here, it is assumed that the BT address (identifier) of power transmission device 100 obtained from pulse 506 is "aa aa aa aa aa aa". Then, the power receiving device 101 starts up the BT (communication unit 119) (S1313).
On the other hand, when power transmission device 100 detects that the impedance changes before and after time Tb3, it activates BT (communication unit 116) (S1101) and transmits an inquiry message (S1102, 605).
When the power receiving device 100 receives the Inquiry message (YES in S1314), the power receiving device 100 acquires the BT address of the sending device stored in the header section of the Inquiry message, and stores (updates) it in the storage area 901 of the ID storage unit 121. . Then, power transmission device 100 compares the two BT addresses stored in storage areas 900 and 901 of ID storage unit 121 (S1316).
FIG. 9 shows the two BT addresses stored in the ID storage unit 121 at this time. According to FIG. 9, the BT address of storage area 900 and the BT address of storage area 901 are both the BT address of power transmission device 100 and match (YES in S1317). Therefore, in S1318, the power receiving device 101 determines whether it has already been connected to the device corresponding to the BT address stored in the ID storage unit 121. There is no BT connection here yet (NO in S1318). Therefore, the power receiving device 101 transmits an Inquiry response message (response signal) to the Inquiry message transmitted by the device (in this case, the power transmitting device 100) corresponding to the BT address stored in the ID storage unit 121 (S1319, 613 ) (response signal transmission means). That is, the power receiving device transmits an inquiry response message (response signal) after recognizing that it is present in the power transmission range 201.
Upon receiving the Inquiry response message 613 (YES in S1103), the power transmission device 100 determines whether the source of the Inquiry response message is a device that is not connected to BT. Here, since the power transmitting device 100 and the power receiving device 101 are not connected by BT (YES in S1104), the power transmitting device 100 performs authentication processing for the power receiving device 101.
By the way, in the authentication according to the BT standard, a PIN code is used, and the authentication is successful when the PIN codes used by the power transmitting device 100 and the power receiving device 101 are the same. Therefore, the power transmission device 100 uses, for example, its own BT address as the PIN code (S1105). Further, the power receiving device 101 uses the BT address of the power transmitting device 100 acquired from the pulse 506 in S1311 as a PIN code (S1320). Since the PIN code is shared, the authentication is successful and the power transmitting device 100 and the power receiving device 101 can share the same encryption key.
Power transmitting device 100 generates an initialization key based on the authentication procedure of the BT standard (S1106), and transmits a random number generated inside power transmitting device 100 to power receiving device 101 (not shown). Upon receiving the random number, power receiving device 101 generates an initialization key based on the PIN code and the random number.
Next, the power transmitting device 100 transmits the newly generated random number to the power receiving device (S1107). Upon receiving the random number in S1107, power receiving device 101 generates an SRES (Signal Response) message from this random number, the BT address of power transmitting device 100, and the initialization key, and transmits it to power transmitting device 100.
When power transmitting device 100 receives the SRES message (S1108), power transmitting device 100 compares it with the SRES message generated by itself (S1109). Since the PIN codes used by power transmitting device 100 and power receiving device 101 are common as described above, the SRES messages match (YES in S1109) and authentication is successful (YES in S1110 and S1321).
Subsequently, the power receiving device 101 transmits an SDP (Service Discovery Protocol)_inquires message (S1322). When the power transmission device 100 receives the SDP_inquires message (S1112), it transmits an SDP_response message including "Wireless Charger" which is service information that can be provided (S1113). Upon receiving the SDP_response message (S1323), the power receiving device 101 compares whether the service it desires matches the service information acquired in S1323 (S1324). Here, since the power receiving device 101 requests the "Wireless Charger" service to charge the battery that is the load 118, it is determined that they match (YES in S1325).
Since the BT connection with the power receiving device 101 was successful, the control unit 104 updates the device flag 704 to "1" (S1116). Then, the control unit 104 instructs the power receiving device 101 to set the impedance to Hi-Z in order to determine whether the foreign object 202 is present in the power transmission range 201 (S1117). Next, the control unit 104 operates the detection unit 103, performs the processes of S1001, S1004, S1005, S1030, and S1006 already described, and compares the impedance storage unit 110 (S1118).
Here, it is assumed that the power transmission unit 113 transmits the pulse 506 transmitted in S1004 between time Tb4 and Tb5. Here, the state is shown in FIG. 2(c), and the foreign object 202 does not exist in the power transmission range 201. Therefore, the impedance detected by the detection unit 103 from time Ta4 to time Ta5 is equal to Z_init (YES in S1119). Therefore, the control unit 104 determines that the cause of the impedance change detected from time Tb2 to time Tb3 is the power receiving device 101 (S1114), and updates the BT address in the storage area 800 of the ID storage unit 106 to the BT address of the power receiving device 101. (S1115) Note that the BT address of the power receiving device 101 can be obtained from the header of the SDP_response message received in S1112. Here, it is assumed that the BT address (identifier) of the power receiving device 101 is "bb bb bb bb bb bb".
FIG. 12 is an operational flowchart of power transmission control in power transmission device 100. Further, FIG. 14 is an operation flowchart of power reception control in the power reception device 101.
First, at time Tb4, the control unit 104 transmits an instruction to change the impedance to Zo (Zo instruction) to the power receiving device 101 in order to calculate the transmission efficiency between the power transmitting antenna 115 and the power receiving antenna 125 (S1200, 614). Upon receiving the Zo instruction (YES in S1400), power receiving device 101 sets the impedance of power receiving device 101 to Zo (S1401), and transmits a Zo instruction response indicating that the impedance has been set to Zo to power transmitting device 100 (S1402).
Upon receiving the Zo instruction response (S1201), the control unit 104 transmits the pulse 506 from the power transmission antenna 115 (S1202). When power receiving device 101 receives the pulse (YES in S1403), power receiving device 101 transmits a power receiving response indicating a voltage value or a power value to power transmitting device 100 (S1431).
If the power reception response received in S1203 is not zero (S1230), the control unit 104 derives the transmission efficiency (S1204), operates the resonance control unit 114 (S1205), and performs resonance control so that the transmission efficiency reaches its peak. 114. When the transmission efficiency reaches its peak (YES in S1205). The transmission efficiency is compared with a pre-stored threshold value (S1207). If it is equal to or greater than the threshold (YES in S1208), the control unit 104 transmits an efficiency notification (high efficiency) to the power receiving device 101 (S1231), and transmits a Hi-Z instruction (S1232, 616). In this case, pulse power transmission (S1202) for efficiency calculation is not performed thereafter. Upon receiving the efficiency notification (YES in S1405), the power receiving device 101 sets the impedance to Hi-Z (S1432), and sends a Hi-Z instruction response to the power transmitting device 100 indicating that it has received the Hi-Z instruction and has set the impedance to Hi-Z. Send. Note that if it is less than the threshold value (NO in S1208), an efficiency notification (efficiency is low) may be notified (S1220) and control may be performed so as not to transmit power.
Next, the control unit 104 requests power receiving parameters indicating the amount of power requested by the power receiving device 101, the peak voltage that the power receiving circuit 117 can tolerate, etc. from the power receiving device 101 (S1209), and the power receiving device 101 responds to the request (S1408). ). The control unit 104 compares the power reception parameters acquired in S1210 with its own power transmission capacity to determine whether power transmission is possible (S1211). Then, if power transmission is possible (YES in S1221), the control unit 104 operates the detection unit 103, performs the processes of S1001, S1004, S1005, S1030, S1006, and S1011 described above, and compares the impedance storage unit 110. (S1233)
Here, it is assumed that the power transmission unit 113 transmits the pulse 506 transmitted in S1004 between time Tb6 and Tb7. In the state shown in FIG. 2(c), the foreign object 202 does not exist in the power transmission range 201, so the impedance detected by the detection unit 103 from time Ta6 to time Ta7 is equal to Z_init (YES in S1234). Therefore, the control unit 104 notifies the power receiving device 101 of power transmission permission (S1213), and upon receiving the power transmission permission response (S1214), instructs the power receiving device 101 to connect to the charging circuit (S1215).
Note that the reason why the detection unit 103 is operated from time Ta6 to Ta7 is because there is a possibility that the foreign object 202 enters the power transmission range 201 between Tb5 and Tb6. In this manner, the control unit 104 always operates the detection unit 103 to confirm that there is no foreign object 202 before starting power transmission.
When the power receiving device 101 receives the power transmission permission notification (YES in S1409), it transmits a power transmission permission response (S1410). Then, the power receiving device 101 receives the charging circuit connection instruction (S1411), and connects the load switching unit 130 to the load control unit 133 (S1412). Further, the power receiving device 101 activates the load control unit 133 (S1413) and transmits a charging circuit connection response (S1414).
When the control unit 104 receives the charging circuit connection response (S1216), it notifies the start of power transmission, and starts power transmission at time Tb7 (S1217, 617). Then, the control unit 104 updates the hold flag 701 to "0" (S1218) and updates the power transmission flag 700 to "1" (S1219).
The power receiving device 101 starts load impedance control (S1416), and upon receiving the power transmission start notification, starts receiving power (S1416), and displays on the display unit 124 that charging is being performed. At this time, the system is in the state shown in FIG. 2(d), and the system state storage unit 105 is in a state where the flag shown in line 708 is stored.
After time Tb7, the impedance of power receiving device 101 is constant at Zo. Since the power transmission section 113 uses a class E amplifier, the impedance of the DC voltage source detected by the detection section 103 is also constant. Here, Z_tx is the impedance of the DC voltage source when the power transmission device 100 is transmitting power after Tb7, and Z_tx is shown in a square 618.
When power transmission device 100 starts transmitting power (YES in S1000), it resets a second timer that times out in a very short time (for example, several milliseconds) compared to the first timer. Then, when the timeout occurs, the power transmission device performs Z detection.
Here, if a foreign object 202 enters the power transmission range 201 during power transmission, the result of Z detection will show a value different from Z_tx due to the influence of the foreign object 202. At this point, the control unit 104 determines that a foreign object 202 or a new power receiving device not shown in FIG. I understand. Power transmitting device 100 performs a process described below to determine whether the cause of the impedance change is foreign object 202, a new power receiving device, or movement of power receiving device 101.
Since the power transmission flag is "1" (YES in S1019), the power transmitting device 100 notifies the power receiving device 101 that power transmission is suspended until the determination is completed (S1025). Then, after updating the power transmission flag to "0" (S1027), power transmission is stopped (S1026). Then, the power transmitting device 100 issues a Hi-Z instruction to the power receiving device 101 (S1028).
Upon receiving the power transmission suspension notification (YES in S1429), power receiving device 100 transmits a power transmission suspension notification response. At this point, the power receiving device 101 knows that the power transmitting device 100 has suspended power transmission to make a determination, or that the power receiving device 101 itself has moved outside the power transmission range 201. Further, when power transmission is stopped (S1430), the power receiving device 101 no longer knows whether it is within the power transmission range 201, so it erases the BT address stored in the storage area 900 (S1422). Furthermore, upon receiving the power transmission hold notification, the power receiving device 101 does not turn off the charging display even though power transmission has been stopped (S1421). Then, upon receiving the Hi-Z instruction, it is set to Hi-Z (S1423) and then transmits a Hi-Z instruction response.
When power transmitting device 100 receives the Hi-Z instruction response (YES in S1029), power transmitting device 100 updates suspension flag 701 to "1" (S1020). Then, the power transmission device 100 returns to the process of S1100 to perform the determination (S1023). At this point, the system state storage unit 105 is in a state where the flag shown in line 709 is stored.
At this point, the power receiving device 101 is in Hi-Z, so the Z detection performed by the power transmitting device 100 is not affected by the power transmitting device. Therefore, the power transmission device 100 detects the foreign object 202 by the process already described using FIG. 2(a) (S1120). Since the device flag 704 is "1" (YES in S1126), the power transmitting device 100 notifies the power receiving device 101 of the error (S1126). At this point, the system state storage unit 105 is in a state where the flag shown in line 710 is stored. When power receiving device 101 receives the error notification (YES in S1424), it turns off the charging display (S1425) and displays an error on display unit 124 (S1426).
Since the power transmission device 100 operates the detection unit in S1126 and moves on to the processing in S1000 (S1126, S1129), it also detects that the foreign object 202 has been removed, as already explained using FIG. 2(a). can.
When the foreign object 202 is removed, the device flag 704 is "1" (YES in S1016), so the power transmitting device 100 notifies the power receiving device of the error cancellation (S1021). Upon receiving the error notification (S1427YES), the power receiving device 101 moves to S1400 and waits for a Zo instruction. Thereafter, the power transmission device 100 starts transmitting power through the process described using FIG. 6(b).
Further, if a new power receiving device enters the power transmission range 201 during power transmission, the result of Z detection shows a value different from Z_tx due to the influence of the new power receiving device. Then, the power transmitting device 100 can detect a new power receiving device by the process already described using FIG. 2(b). Then, in S1200, the Zo instruction is given to all BT addresses stored in the storage area 800 at this point. That is, the Zo instruction is given to the BT address of the power receiving device 101 and the BT address of the new power receiving device. Then, the power transmitting device 100 starts transmitting power to the power receiving device 101 and the new power receiving device. It is preferable that the power receiving device 101 not turn off the charging display while the power transmitting device 100 makes the determination in S1421, that is, if there is a possibility that power can continue to be received even though power transmission has been stopped. As a result, even if a new power receiving device frequently enters the power transmission range 201, the charging display does not turn off each time, and the user of the power receiving device 101 does not feel anxious that charging is not possible.
Note that, for example, if there is another BT device in the power transmission range 201 that can respond to the Inquiry message but does not share information, the answer in S1109 is NO, and the power transmission device 100 identifies the other BT device as a foreign object (S1120). ).
As described above, in the wireless power transmission system according to the first embodiment, the detection unit 103 detects the output of the DC voltage source 401 in a state (initial state) in which both the foreign object 202 and the power receiving device 101 are not present in the power transmission range 201. The impedance was stored as Z_init. Then, by periodically transmitting power pulses via the power transmission antenna 115 and comparing the output impedance at that time with Z_init, it becomes possible to realize foreign object detection without adding a special circuit.
Additionally, a function for controlling impedance is provided in the power receiving device 101. By controlling the impedance of the power receiving device 101 according to instructions from the power transmitting device 100, the power transmitting device 100 can determine which of the foreign object 202 and the power receiving device 101 is present in the power transmission range 201. Furthermore, the power transmitting device 100 can transmit power to the power receiving device 101 with better transmission efficiency.
Further, if Z_init and Z_before are not equal in S1234 (NO in S1234), the power transmission device determines that it is a foreign object (S1235, S1120) and prohibits power transmission. By doing this, it is possible to prohibit power transmission when a foreign object enters the power transmission range between time Tb5 and Tb6.
Additionally, if the SRES does not match, the power transmission device determines that it is a foreign object and prohibits power transmission. This applies when a BT device that cannot enjoy Wireless Charger service enters the power transmission range and performs BT authentication processing. In that case, the power transmission equipment can treat the BT device as the same as a foreign object and prevent it from transmitting power.
Furthermore, if the power receiving device does not return the expected response, communication via BT may be stopped. Examples of cases in which an expected response is not returned include cases in which a Zo instruction response is not received from the power receiving device or a case in which a power reception parameter response is not received.
In addition, when the power transmitting device is configured to send a power transmission capability determination notification in S1212 regardless of the determination result, and the power receiving device is configured to transmit a power transmission capability determination response in response to the notification, the power transmission device receives the power transmission capability determination response. This is the case if you don't. Alternatively, the power transmission device may not receive a power transmission permission response or a charging circuit connection response.
Further, in a case where the power receiving device is configured to transmit a power transmission start notification response in response to a power transmission start notification, there is a case in which the power transmission start response is not received, and a Hi-Z instruction response is not received. Further, in a case where the power receiving device is configured to transmit an error notification response in response to an error notification, the power transmitting device does not receive the error notification response. Further, in a case where the power receiving device is configured to transmit an error cancellation notification response in response to an error cancellation notification, there is a case where the power transmission device does not receive the error cancellation notification response. Another example is a case where the power receiving device does not receive an efficiency notification response in a configuration in which it transmits an efficiency notification response in response to an efficiency notification.
In the above case, for example, the power receiving device may have moved out of the communication range for some reason, the power receiving device may have malfunctioned, or the communication unit of the power transmitting device may have malfunctioned. Further, the power transmission device may be configured to stop or prohibit power transmission even when BT communication is disconnected due to deterioration of the radio wave environment or the like. By doing so, power transmission can be stopped or prohibited if control signals cannot be exchanged.
Furthermore, if the power transmitting device does not perform the next expected process, the power receiving device may disconnect the BT, erase the BT address in the storage area 901, and then stop the BT. When the power transmitting device does not perform the expected processing, for example, the power receiving device does not receive a power transmission permission determination, a Hi-Z instruction, a power transmission permission notification, or a charging circuit connection instruction. This is the case.
Further, when the power receiving device is configured to detect the amount of power received from the power transmitting device, there is a case where the power transmission hold notification is not received even though the amount of received power has become 0. Another case is that the power receiving device does not receive the pulse in S1403 (NO in S1403). Note that if the pulse is not received in S1403 (NO in S1403), the power receiving device may notify the power transmitting device of a power reception failure notification indicating that the pulse was not received before disconnecting the BT.
The above case also applies, for example, when a power receiving device existing within the power transmission range is removed or moved outside the power transmission range, or when the power receiving device or the power transmitting device malfunctions. By doing so, it is possible to respond even when an unexpected situation occurs in the power transmitting device and the power receiving device.
Further, by setting the second timer to a minute time, it is possible to immediately detect that the foreign object 202 has entered the power transmission range 201, and to promptly stop power transmission. Further, by setting the first timer to a longer time than the second timer, it is possible to reduce the power consumption of the power transmission device in a state where power is not being transmitted or BT is not activated.
Additionally, when the power transmitting device receives an Inquiry message response, it sets the power receiving device to Hi-Z to check whether a foreign object exists within the power transmission range. By doing so, if a foreign object is present, an error notification can be sent to the power receiving device to notify that power transmission is prohibited.
Additionally, the power transmission equipment performs Z detection prior to efficiency calculation. By doing so, foreign matter can be detected before efficiency calculation is performed, and efficiency calculation can be performed accurately. Furthermore, since the power transmission device performs Z detection before starting power transmission, if a foreign object enters the power transmission range between time Tb5 and Tb6, the intrusion of the foreign object can be recognized before starting power transmission.
Furthermore, even if the power receiving device receives the power transmission hold notification in S1429 and once the power reception stops, the charging display is not turned off until it receives the error notification. By doing so, even if power reception stops once, if there is a possibility that power can be received again, the charging display can remain on. In other words, even when a plurality of power receiving devices enter the power transmission range 201 one after another, the charging display does not turn off each time.
Furthermore, the power receiving device performs the BT authentication process after recognizing that it is present in the power transmission range 201. By doing so, the power transmitting device can recognize that the power receiving device that has successfully passed the BT authentication process exists within the power transmission range 201. Furthermore, since the power receiving device transmits the Inquiry response message after performing recognition, the power transmitting device can recognize that the power receiving device that has transmitted the Inquiry response message exists within the power transmission range. Therefore, the power transmission device can realize communication control with the power reception device existing in the power transmission range 201.
Further, the power transmission device notifies its own BT address via a power transmission antenna used in a power transmission range 201 narrower than the communication range 200. Then, the power receiving device performs authentication processing only with the power transmitting device that has the BT address obtained by the power receiving antenna. By doing so, it is possible to avoid the problem of the power receiving device having a BT connection with another nearby power transmitting device.
Further, the power receiving device stops the communication unit if the next expected instruction or notification is not received from the power transmitting device. By doing so, system malfunctions can be prevented. Furthermore, if the power transmitting device does not receive an expected response from the power receiving device, it also stops the communication unit and stops the power transmission sequence. By doing so, system malfunctions can be prevented.
Further, the power transmission device is configured to start up the communication unit after detecting an impedance change. By doing so, power is not wasted to be supplied to the communication section, and low power consumption can be achieved.
Further, the power receiving device is set to Hi-Z (S1301, S1441) if the remaining battery level is greater than the threshold (NO in S1300, YES in S1418). By doing so, the power receiving device that does not need to be charged does not affect the Z detection performed by the power transmitting device 100. In addition, if the remaining battery level of the power receiving device is greater than the threshold (NO in S1300, YES in S1418), the power receiving device does not make a BT connection with the power transmitting device, and it is possible to reduce the power consumption of the power receiving device and the power transmitting device. .
(Modification 1) Other configurations will be described below, but similar effects can be obtained with any one of the following or a combination thereof.
The high resistance may also be a capacitor that exhibits high impedance at the frequency of the high frequency voltage generated at the receiving antenna. It is also conceivable not to mount the high resistance 127. In this case, the power receiving antenna is in an open state and the current flowing through the power receiving antenna is zero. In other words, the impedance of the power receiving antenna can be made very high. Further, Z_init may not be a certain fixed value, but may be a value including an error with respect to the fixed value. For example, a similar effect can be obtained even with a value of 100 ohms ±3%.
Further, although the pulse has been described as a combination of the detection signal 502 and the BT address signal 503, it may be only the BT address signal 503. Further, although the power transmission device is configured to transmit power intermittently in pulses, the same effect can be obtained even if the power transmission device is configured to transmit power continuously.
In addition, after the power transmitting device sends an error cancellation notification (S1021), the power transmitting device issues an Md-Z instruction to the power receiving device indicating that the impedance should be set to Md-Z, and the power receiving device sets the impedance to Md-Z. Good too. By doing so, the power receiving device can recognize whether or not it is present in the power transmission range 201, thereby preventing system malfunctions.
Furthermore, in the above description, the power transmitting device notifies the power receiving device of its own BT address via the power transmitting antenna. This may be performed by performing a specific operation on the BT address and notifying the BT address. By sharing specific calculations between the power transmitting device and the power receiving device, similar effects can be obtained, and security can be improved. An example of a specific operation is to perform an exclusive OR of a predetermined 6-byte bit string and a BT address (6-byte) bit string.
Moreover, not only the BT address but also the PIN code may be transmitted in pulses. By configuring the PIN code to be changed as appropriate, the complexity of the encryption key increases and security improves.
Furthermore, in the above description, the power transmitting device notifies the power receiving device of its own BT address via the power transmitting antenna. The BT address may be other information that can identify the power transmission device. For example, it may be a random number randomly generated by the power transmission device. In that case, the power transmission device transmits a random number between times Tb2 and Tb3 and adds the random number to the Inquiry message. The same effect can be obtained even if the power receiving device compares the random number received from time Tb2 to Tb3 and the random number added to Inqiry in S1316.
Further, in the BT authentication and encryption key generation process, the power receiving device may respond to the power transmitting device by adding an information element indicating that the power receiving device can enjoy the Wireless Charger service to the Inquiry response message. For example, an information element called Wireless Power Receiver may be added. By performing authentication processing only with the sender of the response that includes the information element among the received inquiry responses, the power transmission device can avoid unnecessary authentication processing with BT devices that cannot enjoy the Wireless Charger service.
Furthermore, in the above description, the power transmitting device operates as a master, and the power receiving device determines whether to respond to an inquiry based on the source address of the inquiry. However, other packets that are transmitted and received before sharing the encryption key in S1111, ie, other packets that expect a response from the slave, may be used. For example, it may be an ID packet that is sent and received when calling (Page).
Further, although the power transmitting device transmits the BT address signal 503, the power receiving device may transmit its own BT address. In that case, the power receiving device applies load modulation to the pulses transmitted by the power transmitting device, for example, by controlling the connection between the antenna changeover switch and the resonant section. As a result, the impedance seen from the power transmitting device to the power receiving device changes, making it possible to transmit BT address information.
In this case, the power transmission device has a configuration including a storage area 900 and a storage area 901. The power transmitting device stores the BT address of the power receiving device received through load modulation in a storage area 900, and stores the BT address of the power receiving device that is the source of the inquiry response message in a storage area 901. Then, the power transmitting device compares the BT addresses in the process of S1316 and performs authentication and encryption key generation processes on the matched BT addresses. In this case, since BT authentication processing is performed only with power receiving devices existing in the power transmission range 201, the SRESs are sure to match, and unnecessary authentication processing with other BT devices is not performed.
Further, both the power transmitting device and the power receiving device may transmit their respective BT addresses from the power transmitting antenna and the power receiving antenna. In this case, both the power transmitting device and the power receiving device have a storage area 900 and a storage area 901. Upon receiving the BT address signal 503 of the power transmitting device at time T3 in FIG. 5, the power receiving device subsequently transmits the BT address of the power receiving device. In this case, the power receiving device sends an inquiry response only to the power transmitting devices existing in the power transmission range 201. Furthermore, since the power transmitting device performs authentication processing only with power receiving devices existing within the power transmission range 201, there is an effect that unnecessary processing such as performing authentication processing with BT devices that cannot enjoy the Wireless Charger service does not occur.
(Modification 2) Furthermore, the same effect can be obtained even if the communication unit 116 and the communication unit 119 are compatible with a communication standard other than the BT standard, such as a wireless LAN. In the case of a wireless LAN, it is best to configure it by replacing the BT address with a MAC address, the Inquiry message with a ProbeRequest message, and the Inquiry response message with a ProbeResponse message.
For example, the Wi-Fi Direct Service standard (hereinafter referred to as the WFDS standard), which is being considered for standardization by the Wi-Fi Alliance, can be used for authentication and connection processing. The WFDS standard is a protocol that can perform authentication and connection processing between one wireless LAN access point and one station. Further, both the power transmitting device and the power receiving device are configured to transmit their respective MAC addresses from the power transmitting antenna and the power receiving antenna.
Then, the power transmitting device and the power receiving device start WFDS if the MAC addresses stored in the storage area 900 and the storage area 901 match. Then, if the power transmitting device and the power receiving device perform authentication and connection processing only with the wireless LAN device that has the MAC address stored in the storage area 900 and storage area 901, respectively, the power transmitting device will be within the power transmission range. Communication control can be performed with existing power receiving devices.
Here, in a system that transmits and receives control signals using a wireless LAN, consider a case where a plurality of power receiving devices exist within the power transmission range 201. Suppose that a certain power receiving device operating as an access point goes out of the communication range 200 for some reason. Then, the wireless LAN connection between the power transmitting device and the power receiving device operating as an access point is disconnected. Therefore, the power transmitting device becomes unable to transmit and receive control signals to and from the remaining power receiving devices. Therefore, it is desirable to configure the power transmission device to operate as an access point.
However, a wireless LAN terminal that supports the WFDS standard can function as either a station or an access point. The role of a station or an access point is determined in the Group Negotiation phase (hereinafter referred to as GN phase) in the WFDS standard. Furthermore, according to the WFDS standard, a device with a larger intent value between 0 and 15 that is transmitted and received in the GN phase plays the role of an access point, and a device with a smaller intent value plays the role of a station.
Therefore, the intent value transmitted by the power transmitting device is preferably larger than the intent value transmitted by the power receiving device. As an example, the power transmitting device 100 sets the intent value to be transmitted to the power receiving device 101 in the GN phase to be "15", and the power receiving device 101 sets the intent value to be transmitted to the power transmitting device 100 in the GN phase to be "0", so that the power transmitting device Reference numeral 100 can operate as an access point, and power receiving device 101 can operate as a station.
Further, although the WFDS standard has been described as an example of a protocol for performing authentication and connection processing, the Wi-Fi Direct standard may also be used.
Further, although the power transmitting device and the power receiving device both transmit their respective MAC addresses from the power transmitting antenna and the power receiving antenna, this may be configured to be transmitted by either the power transmitting device or the power receiving device. In this way, the power transmitting device can perform communication control with the power receiving device existing within the power transmittable range based on the wireless LAN standard, and it becomes possible for the power transmitting and receiving devices to identify each other.
(Other Embodiments) The present invention can also be realized by executing the following processing. That is, the software (program) that realizes the functions of the embodiments described above is supplied to a system or device via a network or various storage media, and the computer (or CPU, MPU, etc.) of the system or device reads the program. This is the process to be executed.
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Every citation, both ways
| Document | Relation | Office |
|---|---|---|
| JP201145190A | Cites | Japan |
27 members in 7 offices
Priority claims2
| Document | Office | Kind | Date |
|---|---|---|---|
| 2013088880 | Japan | A | |
| 2020000513 | Japan | A |
Members27
| Document | Office | Kind | |
|---|---|---|---|
| WO2014171348A1 | World Intellectual Property Organization (WIPO) | A1 | |
| JP2014212662A | Japan | A | |
| CN105122576A | China | A | |
| KR20150143654A | Republic of Korea | A | |
| US2016006263A1 | United States of America | A1 | |
| EP2987219A1 | European Patent Office (EPO) | A1 | |
| RU2015149623A | Russian Federation | A | |
| RU2621060C2 | Russian Federation | C2 | |
| JP2018033317A | Japan | A | |
| KR101848984B1 | Republic of Korea | B1 | |
| US9948148B2 | United States of America | B2 | |
| US2018205270A1 | United States of America | A1 | |
| CN105122576B | China | B | |
| EP2987219B1 | European Patent Office (EPO) | B1 | |
| US10483809B2 | United States of America | B2 | |
| US2020036234A1 | United States of America | A1 | |
| JP2020054231A | Japan | A | |
| JP6894988B2 | Japan | B2 | |
| US11101703B2 | United States of America | B2 | |
| JP2021122175A | Japan | A | |
| US2021359554A1 | United States of America | A1 | |
| JP2023080239A | Japan | A | |
| US2023268781A1 | United States of America | A1 | |
| US11764620B2 | United States of America | B2 | |
| JP7422706B2This record | Japan | B2 | |
| JP7504257B2 | Japan | B2 | |
| US12119676B2 | United States of America | B2 |
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Numbers
- Publication
- 7422706
- Application
- 94574
Titles2
- Japanese
- 受電装置およびその制御方法
- English
- Power receiving device and its control method
Classification
- CPC, 4
- H02J50/80
- H02J50/60
- H02J50/12
- H02J7/47
- IPC, 5
- H02J50 60
- H02J50 12
- H02J50 80
- H02J4 25
- H02J7 00
