Power transmission coil unit and power supply system

Abstract

To provide a power transmission coil unit and power supply system that enables wireless power transfer while driving with the simplest possible configuration. [Solution] In a wireless power supply system that provides power while in motion, the power transmission coil unit comprises a power transmission coil equipped with a power transmission coil that transmits high-frequency power from a power transmission device, and a power receiving coil mounted on a mobile body that receives the high-frequency power transmitted from the power transmission coil unit, the system includes a detection unit that detects whether or not an object exists within the power transmission range of the power transmission coil unit, and if an object exists, the detection unit determines whether the object is the power receiving coil or an object other than the power receiving coil, and if the detection unit determines that the object is the power receiving coil, it supplies high-frequency power from the power transmission device to the power transmission coil, and if the detection unit determines that the object is an object other than the power receiving coil, it stops supplying high-frequency power from the power transmission device to the power transmission coil.

Description

Technical Field

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[0001] The present invention relates to a power transmission coil unit and a power supply system that realize wireless power supply during driving.

Background Art

[0002] Wireless power supply systems for electric vehicles have been put into practical use. There has been proposed a type of wireless power supply system that not only installs a power transmission coil unit in a parking area but also buries a plurality of power transmission coil units on the road surface to realize power supply during the driving of an electric vehicle.

[0003] When power transmission is carried out in a state where a metal foreign object exists on the power transmission coil unit, power is absorbed by the metal foreign object. Therefore, when a metal foreign object exists on the power transmission coil unit, it is necessary to stop power transmission. Patent Document 1 proposes providing a foreign object detection unit in a power transmission coil unit installed in a parking lot area and stopping power transmission when a foreign object is detected.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] <OO00031>The present invention has been made in view of such circumstances, and an object thereof is to provide a power transmission coil unit and a power supply system that realize wireless power supply during driving with a configuration as simple as possible.

Means for Solving the Problems

[0007] In one embodiment of the present disclosure, the power transmission coil unit is a wireless power supply system that provides power while in motion, comprising a power transmission coil unit equipped with a power transmission coil that converts high-frequency power from a power transmission device into high-frequency magnetic flux for power transmission, and a power receiving coil mounted on a mobile body that receives high-frequency power transmitted from the power transmission coil unit, wherein the system includes a detection unit that detects whether or not an object exists within the power transmission range of the power transmission coil unit, and if an object exists, the detection unit determines whether the object is the power receiving coil or an object other than the power receiving coil, and if the detection unit determines that the object is the power receiving coil, it supplies high-frequency power from the power transmission device to the power transmission coil, and if the detection unit determines that the object is an object other than the power receiving coil, it stops supplying high-frequency power from the power transmission device to the power transmission coil. [Effects of the Invention]

[0008] According to this disclosure, a power transmission coil unit and power supply system can be realized that enables wireless power transfer while driving with the simplest possible configuration. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram of the wireless power supply system in the first embodiment. [Figure 2] This is an explanatory diagram of the wireless power supply system in the first embodiment. [Figure 3] This is a flowchart illustrating an example of the processing performed by the control unit in the first embodiment. [Figure 4] This is a composite diagram showing a schematic representation of the vehicle's power supply status in the first embodiment and a timing chart of object detection and switch opening / closing of the power transmission coil unit. [Figure 5] This is an explanatory diagram of a wireless power supply system in a second embodiment. [Figure 6] This is an explanatory diagram of the wireless power supply system in the third embodiment. [Figure 7]This is a schematic diagram of the wireless power supply system in the third embodiment. [Figure 8] This is a flowchart illustrating an example of the processing performed by the control unit in the third embodiment. [Figure 9] This is a schematic diagram of the wireless power supply system in the fourth embodiment. [Modes for carrying out the invention]

[0010] A power transmission coil unit and a power supply system according to embodiments of this disclosure will be described below with reference to the drawings. This disclosure is not limited to these examples, but is intended to include all modifications within the meaning and scope of the claims, as indicated by the claims. At least some of the embodiments described below may be combined in any way.

[0011] (First Embodiment) Figure 1 is a schematic diagram of a wireless power supply system 100 in a first embodiment. The wireless power supply system 100 includes a plurality of power transmission coil units 1 and a power transmission device 2. Each of the plurality of power transmission coil units 1 has a flat plate shape and is buried under the road surface R in the direction of travel of the vehicle V. The power transmission device 2 is connected to a commercial power source or a power generation system and supplies power to the power transmission coil units 1.

[0012] Vehicle V is an electric vehicle equipped with a receiving coil on its underside that receives high-frequency power transmitted from the power transmission coil unit 1. While traveling on a road R, vehicle V can receive power from the power transmission coil unit 1 via the receiving coil and charge its battery while staying on the power transmission coil unit 1. In the following examples, we will use the case where vehicle V is a four-wheeled electric vehicle equipped with a receiving coil as an example, but vehicle V is not limited to a four-wheeled electric vehicle; it can be any mobile body equipped with a receiving coil.

[0013] FIG. 2 is an explanatory diagram of the wireless power supply system 100 in the first embodiment. In the example of FIG. 2, for simplicity of explanation, one power transmission coil unit 1 connected to the power transmission device 2 is shown, but a plurality of power transmission coil units 1 are connected to the power transmission device 2. Each power transmission coil unit 1 and the power transmission device 2 are connected by a power transmission electric wire, and the power transmission device 2 supplies power to each power transmission coil unit 1.

[0014] The power transmission coil unit 1 has a substantially rectangular parallelepiped housing surrounded by a bottom plate, a top plate, and side plates made of a non-magnetic material with excellent heat dissipation properties, and houses a power transmission coil 11, a detection unit 12, and a switching unit 13 inside the housing.

[0015] The power transmission coil 11 converts the high-frequency power supplied from the power transmission device 2 into a high-frequency magnetic flux and wirelessly transmits power to the power reception coil. The power transmission coil 11 is a coil formed by winding a litz wire obtained by bundling a plurality of conductors and covering them so that the diameters are different on the same coaxial line. The power transmission coil 11 may be formed so as to be wound a plurality of times with the same diameter. The power transmission coil 11 may be wound not only in a circular shape but also in a shape such as a regular polygon, an ellipse, or an oval. The power transmission coil 11 is directly or indirectly connected to the power transmission electric wire connected to the power transmission device 2.

[0016] The detection unit 12 detects and determines whether an object exists in the power transmission range of the power transmission coil unit 1. The detection unit 12 includes a metal sensor 121, a control unit 122, and a storage unit 123. The metal sensor 121 is provided upward of the power transmission coil 11 to detect an object above the power transmission coil unit 1. For example, a coil sensor is used for the metal sensor 121. The coil sensor is installed above the power transmission coil unit 1 with an axis perpendicular to the ground similar to the power transmission coil 11. The coil sensor generates a high-frequency magnetic field around it by the supplied high-frequency current. When an object exists in the high-frequency magnetic field, a magnetic flux change ΔΦ occurs. The metal sensor 121 outputs a signal S that is positively correlated with the magnetic flux change ΔΦ.

[0017] The magnetic flux change ΔΦ varies depending on the properties, size, and distance to the power transmission coil unit 1 of the object existing above the power transmission coil unit 1. For example, compared to the case where plastic exists on the power transmission coil unit 1, when a metal such as iron exists, the magnetic flux change ΔΦ becomes larger. Even for the same metal, when a larger metal exists above the power transmission coil unit 1, the magnetic flux change ΔΦ becomes larger. Even for metals of the same size, when the metal exists closer to the power transmission coil unit 1, the magnetic flux change ΔΦ becomes larger.

[0018] Therefore, when a metallic foreign object F exists directly above the power transmission coil unit 1, a large magnetic flux change ΔΦ occurs, so the level of the signal S output from the metal sensor 121 is relatively high. When a traveling vehicle V passes by, since the power receiving coil is at a position separated from the power transmission coil unit 1 by the vehicle height, the magnetic flux change ΔΦ is smaller compared to when the metallic foreign object F exists directly above, and the level of the signal S output from the metal sensor 121 is relatively low.

[0019] The control unit 122 of the detection unit 12 includes a discrimination unit that discriminates the object above the power transmission coil unit 1 from the level of the signal S captured by the metal sensor 121 for the magnetic flux change ΔΦ above the power transmission coil unit 1. The control unit 122 includes arithmetic elements such as a CPU (Central Processing Unit) or MPU (Micro Processing Unit), and storage elements such as a RAM (Random Access Memory) or ROM (Read Only Memory). A control program is stored in the storage element.

[0020] The control unit 122, when an object is present on the power transmission coil unit 1, determines whether the object is a power receiving coil or an object other than a power receiving coil based on the signal level or waveform of the signal (current) output by the metal sensor 121 corresponding to the object, and outputs the determination result. The control unit 122 transmits a signal corresponding to the determination result to the switching unit 13. While the control unit 122 has determined that a power receiving coil is present on the power transmission coil 11 based on the level or waveform of the signal S from the metal sensor 121, it outputs a power receiving coil determination signal to the switching unit 13. The storage unit 123 includes RAM or ROM.

[0021] The switching unit 13 has a switch that switches the start and stop of power supply from the power transmission device 2 to the power transmission coil 11 in accordance with the power receiving coil discrimination signal output from the control unit 122 of the detection unit 12. The switch can be, for example, a contact relay switch (mechanical relay switch) or a non-contact relay switch such as a MOSFET relay switch. When the switching unit 13 closes the switch, the power transmission coil 11 receives power supply from the power transmission device 2. The switching unit 13 closes the switch while the power receiving coil discrimination signal is output from the control unit 122, and opens the switch when the power receiving coil discrimination signal is not output.

[0022] The memory unit 123 stores rewritable values ​​that are referenced in the processing of the control unit 122. The memory unit 123, which stores data for making decisions based on the signal S output from the metal sensor 121, stores the first threshold Th1 and the second threshold Th2.

[0023] The first threshold Th1 and the second threshold Th2 are specific values ​​of the signal S that can be arbitrarily set by the installer of the power transmission coil unit 1. The second threshold Th2 is a lower value than the first threshold Th1. In the following description, a signal S output from the metal sensor 121 at a level of the first threshold Th1 or higher will be referred to as a strong signal, a signal S output from the metal sensor 121 at a level less than the first threshold Th1 and greater than the second threshold Th2 will be referred to as a medium signal, and a signal S output from the metal sensor 121 at a level of the second threshold Th2 or lower will be referred to as a weak signal.

[0024] If the signal S output from the metal sensor 121 is a strong signal, the control unit 122 determines that a metallic foreign object F is present on the power transmission coil unit 1. If the signal S output from the metal sensor 121 is a medium signal, the control unit 122 determines that a power receiving coil is present on the power transmission coil unit 1. If the signal S output from the metal sensor 121 is a weak signal, the control unit 122 determines that there is no object on the power transmission coil unit 1, or that there is an object other than the power receiving coil and the metallic foreign object F. In other words, if the signal S output from the metal sensor 121 is a strong or weak signal, the control unit 122 determines that there is an object other than the power receiving coil on the power transmission coil unit 1.

[0025] Figure 3 is a flowchart illustrating an example of the processing performed by the control unit 122 in the first embodiment. The control unit 122 performs the following processing according to the set sampling rate.

[0026] The control unit 122 determines whether the signal S output from the metal sensor 121 is a medium signal at a level less than the first threshold Th1 and greater than the second threshold Th2 (step S101). If the control unit 122 determines that the signal S is a medium signal (step S101: YES), it determines that the power receiving coil has been identified (step S102). The control unit 122 outputs a power receiving coil identification signal (step S103), closes the switch, and causes the power transmission device 2 to supply power to the power transmission coil 11, thus ending the processing for one sampling cycle.

[0027] If the control unit 122 determines that signal S is not a medium signal (step S101: NO), it determines that it did not identify the power receiving coil (step S104). If the control unit 122 is outputting a power receiving coil identification signal, it stops outputting it (step S105), stops supplying power from the power transmission device 2 to the power transmission coil 11, and ends the processing for one sampling cycle.

[0028] The power transmission to the vehicle V by the power transmission coil unit 1 in the first embodiment will be explained using a specific example. Figure 4 is a composite diagram of a schematic diagram of the power supply state of the vehicle V in the first embodiment and a timing chart of object detection and switch opening / closing of the power transmission coil unit 1. In the schematic diagram of Figure 4, for the sake of simplification, only one power transmission coil unit 1 installed in parallel in the ground of the road R is shown, and the power transmission device 2 is omitted. A solid line vehicle V represents a vehicle V that is not receiving power, and a dotted line vehicle V represents a vehicle V that is receiving power.

[0029] In the timing chart in Figure 4, the horizontal axis represents elapsed time t. The vertical axis of the upper timing chart represents the level of signal S corresponding to the detected magnetic flux change ΔΦ. The vertical axis of the lower timing chart represents the open / closed state of the switch of the switching unit 13.

[0030] Point P1 in Figure 4 indicates a moment when the vehicle V is approaching the power transmission coil unit 1. Since the signal S is a weak signal, the control unit 122 determines that the signal S at P1 is not a medium signal and therefore determines that the power receiving coil could not be identified. Consequently, the power receiving coil identification signal is not transmitted, the switch is opened, and no power is supplied from the power transmission device 2 to the power transmission coil 11.

[0031] Point P2 in Figure 4 indicates a point in time when the vehicle V is positioned above the power transmission coil unit 1. The control unit 122 determines that the signal S at P2 is a medium signal. Therefore, the control unit 122 determines that it has identified the power receiving coil and outputs a power receiving coil identification signal to the switching unit 13, thereby closing the switch and supplying power from the power transmission device 2 to the power transmission coil 11.

[0032] Point P3 in Figure 4 indicates a point in time when the vehicle V is separated from the power transmission coil unit 1. Since signal S is a weak signal, the control unit 122 determines that signal S at P3 is not a medium signal and that the power receiving coil could not be identified. Therefore, the power receiving coil identification signal is not transmitted, the switch is opened, and power is not supplied from the power transmission device 2 to the power transmission coil 11.

[0033] Point P4 in Figure 4 indicates a point in time when no metallic foreign object F is present on the power transmission coil unit 1. Since the signal S is a weak signal, the control unit 122 determines that the signal S at P4 is not a medium signal and that the power receiving coil was not identified. Therefore, the power receiving coil identification signal is not transmitted, the switch is opened, and power is not supplied from the power transmission device 2 to the power transmission coil 11.

[0034] Point P5 in Figure 4 indicates a point in time when a metallic foreign object F is present on the power transmission coil unit 1. Since the signal S is a strong signal, the control unit 122 determines that the signal S at P5 is not a medium signal and therefore determines that the power receiving coil could not be identified. Consequently, the power receiving coil identification signal is not transmitted, the switch is opened, and power is not supplied from the power transmission device 2 to the power transmission coil 11.

[0035] Based on the above, a simple power transmission coil unit 1 can be realized that can distinguish and detect two different objects, a vehicle V and a metallic foreign object F, using a single detection unit 12.

[0036] (Second Embodiment) In the second embodiment, the switching of power supply from the power transmission device 2 to the power transmission coil 11 by the switching unit 13 is performed by the control unit of the power transmission device 2. Unless otherwise specified below, the same terms as in the first embodiment refer to the same terms as in the first embodiment, and parts that are not explained are the same as in the first embodiment.

[0037] The wireless power supply system 100 in the second embodiment has the same configuration as in the first embodiment, as shown in Figure 1. Figure 5 is an explanatory diagram of the wireless power supply system 100 in the second embodiment. Two or more power transmission coil units 1 may be connected to the power transmission device 2. In the second embodiment, each power transmission coil unit 1 and the power transmission device 2 are connected not only to enable power transmission by power transmission wires, but also by communication lines. Note that the connection is not limited to wired connections, but may also be wireless.

[0038] The power transmission coil unit 1 includes a power transmission coil 11, a detection unit 12, and a communication unit 14. The detection unit 12 does not have a control unit 122 or a storage unit 123. The signal S output by the metal sensor 121 is received by the communication unit 14.

[0039] The communication unit 14 communicates with the power transmission device 2 via a wired connection using signal lines or communication lines. The communication unit 14 may also communicate with the power transmission device 2 via wireless communication such as Bluetooth® or Wi-Fi®. The communication unit 14 is connected to the communication unit 21 of the power transmission device 2, which will be described later. The communication unit 14 transmits the signal S output by the metal sensor 121 to the communication unit 21.

[0040] The power transmission device 2 includes a communication unit 21, a control unit 22, a storage unit 23, and a switching unit 24. The communication unit 21 receives communications from the power transmission coil unit 1 via a wired connection using signal lines or communication lines. The communication unit 21 may also receive communications wirelessly, such as Bluetooth® or Wi-Fi®. The communication unit 21 has the same configuration as the communication unit 14 and receives the signal S output by the metal sensor 121 received by the communication unit 14. Only one communication unit 21 is provided in the power transmission device 2, but two or more may be provided.

[0041] The control unit 22 includes an arithmetic element such as a CPU or MPU, and a memory element such as RAM or ROM. The control unit 22 receives signals S output by the metal sensor 121 of each power transmission coil unit 1 via the communication unit 21. The control unit 22 controls the switching unit 24 by transmitting signals to switch the power supply to the power transmission coils 11 of the multiple power transmission coil units 1 on and off. In the second embodiment, only one control unit 22 is provided in the power transmission device 2, but the number of control units 22 is not limited to this. The memory unit 23, which includes RAM or ROM, stores signals for a fixed period of time that are output by the metal sensor 121 and received by the control unit 22.

[0042] The switching unit 24 is equipped with switches for switching the power supply to the corresponding power transmission coils 11 on and off, according to the number of power transmission coil units 1 connected to the power transmission device 2. The switching unit 24 switches each switch on and off by receiving a signal from the control unit 22 to switch the opening and closing of a specific switch. Each switch may be, for example, a contact relay switch (mechanical relay switch) or a non-contact relay switch such as a MOSFET relay switch.

[0043] In the second embodiment, the control unit 22 performs the same function as the control unit 122 in the first embodiment, the storage unit 23 performs the same function as the storage unit 123 in the first embodiment, and the switching unit 24 performs the same function as the switching unit 13 in the first embodiment. The signal S output by the metal sensor 121 is transmitted to the power transmission device 2, and the control unit 22 performs object identification and outputs a power receiving coil identification signal based on the signal S. The control unit 22 performs the same processing as described with reference to Figure 3 of the first embodiment, and if it determines that a power receiving coil is present on the power transmission coil unit 1 (step S101: YES), it outputs a power receiving coil identification signal (step S103).

[0044] In the second embodiment, the power transmission device 2 switches the start and stop of power supply to the power transmission coil 11. The switches can be controlled collectively by the power transmission device 2.

[0045] Based on the above, a wireless power supply system 100 with a simpler configuration having only one control unit is provided, in which the switching of power supply from the power transmission device 2 to the power transmission coil 11 is performed by the control unit 22 and switching unit 24 provided in the power transmission device 2.

[0046] (Third embodiment) In the third embodiment, the power transmission coil unit 1 that has identified vehicle V sends a power receiving coil identification notification to other power transmission coil units 1, and when the other power transmission coil units 1 that have received the notification identify vehicle V, they transmit power. Unless otherwise specified below, the same terms as in the first embodiment refer to the same terms as in the first embodiment, and parts that are not explained are the same as in the first embodiment.

[0047] The wireless power supply system 100 in the third embodiment has the same configuration as in the first embodiment, as shown in Figure 1. Figure 6 is an explanatory diagram of the wireless power supply system 100 in the third embodiment. Three or more power transmission coil units 1 may be connected to the power transmission device 2.

[0048] In the third embodiment, a code ending in "A" indicates the configuration or operation of the power transmission coil unit 1A, a code ending in "B" indicates the configuration or operation of the power transmission coil unit 1B, and a code ending in "C" indicates the configuration or operation of the power transmission coil unit 1C.

[0049] The power transmission coil unit 1A includes a power transmission coil 11A, a detection unit 12A, a switching unit 13A, and a communication unit 14A. The communication unit 14A has the same configuration as the communication unit 14 in the second embodiment. The communication unit 14A is connected to the control unit 122A and the control unit 122B of the power transmission coil unit 1B in a communicative manner. The power transmission coil unit 1B has the same structure as 1A, and the communication unit 14B is connected to the control unit 122C in a communicative manner.

[0050] The memory unit 123 of each power transmission coil unit 1 stores a first threshold Th1, a second threshold Th2, and a predetermined period T. The predetermined period T is a period that can be arbitrarily set by the installer of each power transmission coil unit 1. The predetermined period T may be the estimated time required for a vehicle V to pass over each power transmission coil unit 1. For example, if a roughly square power transmission coil unit 1 of 1m x 1m is buried in a road R on which a vehicle V is expected to travel at 20km / h, the predetermined period T can be set to, for example, 0.18 seconds. In addition, the memory unit 123 stores the power receiving coil identification notification, which will be described later, along with the reception time.

[0051] Figure 7 is a schematic diagram of the wireless power supply system 100 in the third embodiment. Figure 7A is a schematic diagram when the vehicle V is on the power transmission coil unit 1. As shown in Figure 7A, in the third embodiment, power transmission coil units 1B, 1C, 1D, etc. are embedded in a line on the side of the vehicle V in the direction of travel, starting from power transmission coil unit 1A. Therefore, the vehicle V travels on each power transmission coil unit 1 in the order of power transmission coil units 1A, 1B, 1C, etc.

[0052] Figure 8 is a flowchart illustrating an example of the processing performed by the control unit 122B in the third embodiment. The control unit 122B performs the following processing according to the set sampling rate.

[0053] As shown by the dashed arrow in Figure 7A, when the control unit 122A determines that the signal SA is a medium signal at a level below the first threshold Th1 and above the second threshold Th2, the communication unit 14A sends a power receiving coil identification notification to the power transmission coil unit 1B. The received notifications are stored in the storage unit 123B in chronological order.

[0054] The control unit 122B determines whether the signal SB output from the metal sensor 121B is a medium signal at a level less than the first threshold Th1 and greater than the second threshold Th2 (step S201). If the signal SB is determined to be a medium signal (step S201: YES), the control unit 122B determines that it has identified the power receiving coil (step S202), and the communication unit 14B sends a power receiving coil identification notification signal to the power transmitting coil unit 1C (step S203).

[0055] The control unit 122B refers to the storage unit 123B (step S204) and determines whether or not it received and stored a power receiving coil identification notification from the power transmission coil unit 1A during a predetermined period T prior to the sampling time of the signal S (step S205).

[0056] In Figure 7, the power transmission coil unit 1 during power transmission is shown in gray. As shown in Figure 7A, if the vehicle V has passed over the power transmission coil unit 1A, it is determined that a notification has been received and stored from the power transmission coil unit 1A during a predetermined period T (step S205: YES). Therefore, the control unit 122B outputs a power receiving coil discrimination signal (step S206), closes the switch, and causes the power transmission device 2 to supply power to the power transmission coil 11, thus ending the processing for one sampling.

[0057] Figure 7B is a schematic diagram showing what happens when a metallic foreign object F appears after falling onto the road R. Since the metallic foreign object F does not pass over the power transmission coil unit 1A, no notification is stored in the memory unit 123B. Therefore, the control unit 122B determines that it did not store a notification during the predetermined period T (step S205: NO) and determines that it could not identify the power receiving coil (step S207). If the control unit 122B is outputting a power receiving coil identification signal, it stops the power receiving coil identification signal (step S208), stops the power supply from the power transmission device 2 to the power transmission coil 11, and ends the processing for one sampling.

[0058] If the control unit 122B determines that signal S is not a medium signal (step S201: NO), the control unit 122B determines that it has not identified the power receiving coil (step S207). If the control unit 122 is outputting a power receiving coil identification signal, it stops the power receiving coil identification signal (step S208), stops the power supply from the power transmission device 2 to the power transmission coil 11, and ends the processing for one sampling.

[0059] Based on the above, a simple power transmission coil unit 1 can be realized that transmits power only during periods when it is highly likely to receive notification from other power transmission coil units 1 and to identify the receiving coil.

[0060] (modified version) Figure 7C is a schematic diagram of this modified example. The power transmission coil unit 1 during power transmission is shown in gray. As shown in Figure 7C, a configuration may be used in which power receiving coil identification notifications are made between three or more power transmission coil units 1. For example, power transmission coil unit 1A may send power receiving coil identification notifications to 1B and 1C, and power transmission coil unit 1B may send power receiving coil identification notifications to 1C and 1D. Power transmission coil unit 1C may output a power receiving coil identification signal if it has received notifications from power transmission coil units 1A and 1B during a predetermined period T.

[0061] In the third embodiment, instead of transmitting a power receiving coil identification notification, the control unit 122 may forward the output medium signal S to another power transmitting coil unit via the communication unit 14, and the storage unit 123 may store the signal S. The control unit 122B may refer to the level of the signal SA stored in the storage unit 123B, and if the level of the output signal SB is the same as the level of the stored signal SA, it may identify the power receiving coil and output a power receiving coil identification signal. A configuration may also be used to perform power receiving coil identification notifications between non-adjacent power transmitting coil units 1, such as power transmitting coil units 1A and 1C.

[0062] (Fourth Embodiment) In the fourth embodiment, the control unit provided in the power transmission device 2 switches the power supply to the power transmission coil 11, and the power transmission coil unit 1 that has identified the power receiving coil transmits power if another power transmission coil unit 1 has identified the power receiving coil within a certain period prior to the identification. Unless otherwise specified below, the same terms as in each embodiment refer to the same terms as in each embodiment, and parts that are not explained are the same as in the third embodiment.

[0063] The wireless power supply system 100 in the fourth embodiment has the same configuration as in the first embodiment, as shown in Figure 1. The configurations of the power transmission coil unit 1 and the power transmission device 2 are the same as in Figure 5, so their description is omitted. In the fourth embodiment, the control unit 22 performs the same role as the control unit 122 in the third embodiment, the storage unit 23 performs the same role as the storage unit 123 in the third embodiment, and the switching unit 24 performs the same role as the switching unit 13 in the third embodiment.

[0064] Figure 9 is a schematic diagram of the wireless power supply system 100 in the fourth embodiment. The power transmission coil unit 1 during power transmission is shown in gray. The control unit 22 performs the same processing as described with reference to Figure 8 of the third embodiment. The signal S output by the metal sensor 121 is transmitted to the power transmission device 2, and the control unit 22 identifies the object from the level of the signal S (step S201). The storage unit 23 stores the determination results of the control unit 22 in chronological order. Note that no power receiving coil determination notification is sent (step S203 omitted). Instead of referring to the notification, the control unit 22 refers to the determination result (step S204), and if it has stored a signal S that is a medium signal during a predetermined period T (step S205: YES), it sends a power receiving coil determination signal (step S206).

[0065] Figure 9 shows the scene at time t2 when the vehicle V approaches the power transmission coil unit 1B. In Figure 9, a medium signal SB is output from the metal sensor 121B to the power transmission device 2, and the power receiving coil is identified. The control unit 22 checks whether it has stored the medium signal SA during the predetermined period T prior to time t2, or it checks the storage unit 23. Since the vehicle V passes over the power transmission coil unit 1A, the storage unit 23 has stored the medium signal SA at least at time t1, which is included within the predetermined period T. Therefore, the control unit 22 outputs a power receiving coil identification signal to close the switch and causes the power transmission device 2 to supply power to the power transmission coil 11. Note that if a metallic foreign object F is present on the power transmission coil unit 1B, the medium signal SB will not be output, the power receiving coil will not be identified, and power will not be supplied to the power transmission coil 11.

[0066] In the fourth embodiment, the power transmission device 2 switches the start and stop of power supply to the power transmission coil 11. The switches can be controlled collectively by the power transmission device 2.

[0067] Based on the above, a simpler power transmission coil unit 1 with only one control unit can be realized, in which the power supply switching from the power transmission device 2 to the power transmission coil 11 is performed by the control unit 22 and switching unit 24 of the power transmission device 2, and power is transmitted only during periods when it is highly likely that it has received notification from other power transmission coil units 1 and has identified the receiving coil.

[0068] In the fourth embodiment, the power transmission of the power transmission coil unit 1 may be controlled by whether or not a signal S originating from any of the power transmission coil units 1 embedded on the power transmission coil unit 1A side of itself is stored. The power transmission of the power transmission coil unit 1 may also be controlled by whether or not two or more signals S are stored, as shown in the modified example of the third embodiment.

[0069] In the fourth embodiment, the control unit 22 may refer to the level of signal SA stored in the storage unit 23 and output a power receiving coil discrimination signal if the level of the output signal SB is the same as the level of the stored signal SA.

[0070] In the third and fourth embodiments, the power transmission coil unit 1A does not receive power receiving coil identification notifications from other power transmission coil units 1, store the signal S, or transmit power via the power transmission coil 11. Therefore, it is sufficient if it is configured to detect objects and transmit power receiving coil identification notifications or the signal S. Accordingly, the power transmission coil unit 1A in the third embodiment may not have a power transmission coil 11 and a switching unit 13, and may not be connected to the power transmission device 2. Similarly, the power transmission coil unit 1A in the fourth embodiment may not have a power transmission coil 11, and the power transmission device 2 may not have a switch for the power transmission coil unit 1A. The power transmission coil unit 1A may be configured not to perform steps S206 and S207, and may still be capable of transmitting power.

[0071] In the first to fourth embodiments, the metal sensor 121 performed object detection based on the level of a signal S that is positively correlated with the magnetic flux change ΔΦ. However, the metal sensor 121 is not limited to a coil sensor. An infrared sensor or an ultrasonic sensor may be used as the metal sensor 121. In this case, the metal sensor 121 receives reflections from a light-emitting unit or an ultrasonic output unit installed facing upwards towards the power transmission coil unit 1. The control unit 122 or control unit 22 can distinguish between the power receiving coil and foreign objects based on the distance and properties of the object, based on the level or waveform of the signal output according to the reflection intensity or reflection wavelength of the reflection received by the metal sensor 121.

[0072] The metal sensor 121 in the first to fourth embodiments may be an image sensor having an imaging device such as a camera. The control unit 122 or control unit 22 can distinguish between a power receiving coil and a foreign object based on the signal level or waveform of the image signal output from the metal sensor 121, which is an image sensor, i.e., the distribution of pixel values.

[0073] In the second to fourth embodiments, even if the control unit 122 or control unit 22 acquires a medium signal, if it had continuously acquired a strong signal for a certain period of time or longer before acquiring the medium signal, it may determine that a foreign object has been identified and stop the power receiving coil identification signal.

[0074] In the first to fourth embodiments, the determination of the presence or absence of an object on the power transmission coil unit 1, and the determination of the power receiving coil versus a foreign object, may be performed based on a machine learning prediction model. For example, the prediction model can be constructed using algorithms such as LSTM (Long Short-Term Memory) or Transformer, and may be constructed by combining multiple algorithms. For example, the prediction model may have an input layer that accepts input data including time-series data of the level of signal S, an intermediate layer that extracts features from the input data, and an output layer that outputs the level of the signal S following the time-series data of the input data. The presence and type of the object may be determined from the output result, and the output and stopping of the power receiving coil discrimination signal may be controlled. [Explanation of Symbols]

[0075] 1: Power transmission coil unit, 2: Power transmission device, 11: Power transmission coil, 100: Wireless power supply system, F: Metal foreign object, R: Road, S: Signal, Th1: First threshold, Th2: Second threshold, t: Time, V: Vehicle

Claims

1. A power transmission coil unit equipped with a power transmission coil that converts high-frequency power from a power transmission device into high-frequency magnetic flux for power transmission, In a receiving coil mounted on a mobile body that receives high-frequency power transmitted from the aforementioned power transmission coil unit, In a wireless power supply system that provides power while driving, The unit includes a detection unit that detects whether or not an object is present within the power transmission range of the power transmission coil unit. The detection unit, if the object is present, determines whether the object is the power receiving coil or an object other than the power receiving coil. If the detection unit determines that the object is the power receiving coil, it supplies high-frequency power from the power transmission device to the power transmission coil. If the detection unit determines that the object is an object other than the power receiving coil, it will stop supplying high-frequency power from the power transmission device to the power transmission coil. A power transmission coil unit characterized by the following.

2. The detection unit is The system includes a metal sensor that outputs a signal corresponding to the metallic material, size, and distance between the power transmission coil unit and the metal, within the power transmission range of the power transmission coil unit. The aforementioned discrimination unit is If the signal level output from the metal sensor is between the first threshold and the second threshold, the object is identified as the power receiving coil. If the signal level output from the metal sensor is equal to or greater than the first threshold, or less than or equal to the second threshold, the object is determined to be an object other than the power receiving coil. A power transmission coil unit according to claim 1, characterized by the following:

3. The discriminant unit is equipped with a communication unit that, when it determines that the substance is the power receiving coil, transmits a signal indicating the detection of the power receiving coil to a power transmission coil unit adjacent to the direction of travel of the moving body. A power transmission coil unit according to claims 1 to 2, characterized by the above.

4. When a signal indicating the detection of the receiving coil is transmitted from an adjacent power transmission coil unit, The high-frequency power from the power transmission device is supplied to the power transmission coil. If the detection unit does not determine that the object is the power receiving coil within a predetermined time, To stop supplying high-frequency power from the power transmission device to the power transmission coil, The power transmission coil unit according to claim 3, characterized by the following:

5. Multiple power transmission coil units are installed side-by-side on the road surface, each equipped with a power transmission coil that converts supplied power into high-frequency magnetic flux for wireless transmission, A power transmission device that supplies power to the aforementioned multiple power transmission coil units Includes, The aforementioned power transmission coil unit is The system includes a sensor unit that outputs a signal corresponding to the properties or size of an object within the power transmission range of the power transmission coil, or the distance to the object. The output signal is transmitted to the power transmission device. The aforementioned power transmission device is When the object is identified as an electric vehicle based on the signal output from the power transmission coil unit, power is supplied to the power transmission coil unit that transmitted the signal. Power supply system.

6. The aforementioned power transmission device is If the object is identified as an electric vehicle based on the first signal output from the first power transmission coil unit, the fact that it was identified as an electric vehicle is stored. If, within a predetermined period after the system has recorded that an electric vehicle has been identified, the system determines that an object is an electric vehicle based on the second signal output from the second power transmission coil unit, then power is supplied to the second power transmission coil unit. The power supply system according to claim 5.

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