Wireless power feeding system, power reception terminal, and power transmitter

Abstract

The present invention addresses the problem of increasing transmission power and improving power efficiency. This power transmitter (1) has a plurality of power transmission coils (10), a plurality of power transmission circuits (11), a first controller (12), and a plurality of first measurement circuits (13). This power reception terminal (2) has a plurality of power reception coils (20), a plurality of power reception circuits (21), a DC output unit (24), a plurality of switches (23), a second controller (22), and at least one second measurement circuit (25). The second measurement circuit (25) measures a voltage and a current related to output power of the plurality of power reception circuits (21). The first controller (12) calculates power efficiency on the basis of information about input power and information about output power, and controls the plurality of power transmission circuits (11) on the basis of information about the output power and information about power efficiency. The second controller (22) controls the plurality of switches (23) on the basis of control information about the plurality of switches (23) from the first controller (12).

Description

Wireless power supply system, power receiving terminal, and power transmitter

[0001] The present disclosure generally relates to a wireless power supply system, a power receiving terminal, and a power transmitter, and more particularly to a wireless power supply system, a power receiving terminal, and a power transmitter that include a power transmitter having a power transmitting coil and a power receiving terminal having a power receiving coil.

[0002] Patent Literature 1 discloses a wireless power transmission system including a power transmitting device having a power transmitting coil and a power receiving device having a power receiving coil. The power transmitting device disclosed in Patent Literature 1 transmits AC power in a contactless manner by electromagnetic induction between the power transmitting coil and the power receiving coil.

[0003] In the wireless power transmission system disclosed in Patent Document 1, it may be difficult to increase the DC power obtained at the power receiving terminal, and the power efficiency may decrease when the power is low.

[0004] JP 2015-111996 A

[0005] An object of the present disclosure is to provide a wireless power feeding system, a power receiving terminal, and a power transmitter that can increase the DC power obtained at the power receiving terminal and improve power efficiency.

[0006] A wireless power supply system according to one aspect of the present disclosure includes a power transmitter and a power receiving terminal. The power receiving terminal is supplied with power from the power transmitter. The power transmitter includes a plurality of power transmitting coils, a plurality of power transmitting circuits, a first controller, and a plurality of first measurement circuits. The plurality of power transmitting circuits correspond one-to-one with the plurality of power transmitting coils. The plurality of power transmitting circuits supply transmitting power to corresponding power transmitting coils among the plurality of power transmitting coils. The first controller controls the plurality of power transmitting circuits. The plurality of first measurement circuits correspond one-to-one with the plurality of power transmitting circuits. The plurality of first measurement circuits measure voltages and currents related to input power of corresponding power transmitting circuits among the plurality of power transmitting circuits. The power receiving terminal includes a plurality of power receiving coils, a plurality of power receiving circuits, a DC output unit, a plurality of switches, a second controller, and at least one second measurement circuit. The plurality of power receiving coils receive AC power from opposing power transmitting coils among the plurality of power transmitting coils. The multiple power receiving circuits correspond one-to-one to the multiple power receiving coils. The multiple power receiving circuits convert AC power received by corresponding power receiving coils among the multiple power receiving coils into DC power. The DC output unit includes a first DC output terminal and a second DC output terminal. The first DC output terminal is commonly connected to high-potential output terminals of the multiple power receiving circuits. The second DC output terminal is commonly connected to low-potential output terminals of the multiple power receiving circuits. The multiple switches correspond one-to-one to the multiple power receiving circuits. The multiple switches are connected between corresponding power receiving circuits among the multiple power receiving circuits and the DC output unit. The second controller controls the multiple switches. The at least one second measurement circuit measures voltages and currents related to output power from the multiple power receiving circuits. The first controller calculates power efficiency based on the input power information and the output power information, and controls the multiple power transmitting circuits based on the output power information and the power efficiency information. The second controller controls the switches based on control information for the switches from the first controller.

[0007] A power receiving terminal according to one aspect of the present disclosure includes a plurality of power receiving coils, a plurality of power receiving circuits, a DC output unit, a plurality of switches, a controller, and at least one measurement circuit. The plurality of power receiving circuits correspond one-to-one to the plurality of power receiving coils and convert AC power received by a corresponding power receiving coil of the plurality of power receiving coils into DC power. The DC output unit includes a first DC output terminal to which high-potential output terminals of the plurality of power receiving circuits are commonly connected and a second DC output terminal to which low-potential output terminals of the plurality of power receiving circuits are commonly connected. The plurality of switches correspond one-to-one to the plurality of power receiving circuits and are connected between a corresponding power receiving circuit of the plurality of power receiving circuits and the DC output unit. The controller controls the plurality of switches. The at least one measurement circuit measures voltages and currents related to output power from the plurality of power receiving circuits. The controller controls the plurality of switches based on control information of the plurality of switches.

[0008] A power transmitter according to one aspect of the present disclosure includes a plurality of power transmitting coils, a plurality of power transmitting circuits, a controller, and a measurement circuit. The plurality of power transmitting circuits correspond one-to-one to the plurality of power transmitting coils and supply transmission power to a corresponding one of the plurality of power transmitting coils. The controller controls the plurality of power transmitting circuits. The plurality of measurement circuits correspond one-to-one to the plurality of power transmitting circuits and measure voltages and currents related to input power of a corresponding one of the plurality of power transmitting circuits. The controller calculates power efficiency based on information about the input power and information about output power of a power receiving terminal, and controls the plurality of power transmitting circuits based on information about the output power and the power efficiency.

[0009] FIG. 1 is a configuration diagram of a wireless power feeding system according to a first embodiment. FIG. 2 is a circuit diagram of a power transmitting circuit included in a power transmitter in the wireless power feeding system. FIG. 3 is a configuration diagram of a first measurement circuit included in a power transmitter in the wireless power feeding system. FIG. 4 is a circuit diagram of a power receiving circuit included in a power receiving terminal in the wireless power feeding system. FIG. 5 is a schematic exploded perspective view of a power transmitter in the wireless power feeding system. FIG. 6 is a schematic plan view of a housing of a power transmitter and a mobile system in the wireless power feeding system. FIG. 7 is a configuration diagram of a wireless power feeding system including a power transmitter according to the first embodiment and a power receiving terminal having only one power receiving coil. FIG. 8 is a flowchart illustrating the operation of a power transmitter according to the first embodiment. FIG. 9 is a flowchart illustrating the operation of the power transmitter in the same embodiment. FIG. 10 is an explanatory diagram of the operation of the wireless power feeding system according to the first embodiment. FIG. 11 is an explanatory diagram of the operation of the wireless power feeding system in the same embodiment. FIG. 12 is a circuit diagram illustrating another example of a power receiving circuit of a power receiving terminal in the wireless power feeding system. Fig. 13 is a circuit diagram showing yet another example of a power receiving circuit of a power receiving terminal in the wireless power feeding system of the same. Fig. 14 is an explanatory diagram of the operation of a wireless power feeding system according to a modified example of embodiment 1. Fig. 15 is a configuration diagram of a wireless power feeding system according to embodiment 2. Fig. 16 is a configuration diagram of a wireless power feeding system according to embodiment 3. Fig. 17 is a configuration diagram of a main part of a power transmitter in the wireless power feeding system of the same. Fig. 18 is a configuration diagram of a main part of a power receiving terminal in the wireless power feeding system of the same. Fig. 19 is a configuration diagram of a wireless power feeding system according to embodiment 4. Fig. 20 is a configuration diagram of a main part of a power transmitter in the wireless power feeding system of the same. Fig. 21 is a configuration diagram of a main part of a power receiving terminal in the wireless power feeding system of the same. Fig. 22 is a configuration diagram of a wireless power feeding system according to embodiment 5. Fig. 23 is an explanatory diagram of the operation of the power receiving terminal according to embodiment 1. Fig. 24 is an explanatory diagram of the operation of the power receiving terminal in the same.

[0010] Hereinafter, embodiments and the like will be described with reference to the drawings. The drawings referred to in the following embodiments and the like are schematic diagrams, and the sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensions, and the size ratios and thickness ratios between the components do not necessarily reflect the actual dimensional ratios.

[0011] First Embodiment A wireless power supply system 3 according to a first embodiment will be described below with reference to FIGS. 1 to 10. FIG.

[0012] (1) Configuration As shown in FIG. 1 , the wireless power feeding system 3 includes a power transmitter 1 and a power receiving terminal 2. The power receiving terminal 2 is fed with power from the power transmitter 1. The power transmitter 1 includes a plurality of (two in the example of FIG. 1 ) power transmitting coils 10, a plurality of (two in the example of FIG. 1 ) power transmitting circuits 11, a first controller 12, and a plurality of (two in the example of FIG. 1 ) first measurement circuits 13. The plurality of power transmitting circuits 11 correspond one-to-one to the plurality of power transmitting coils 10. The plurality of power transmitting circuits 11 supply transmission power to corresponding ones of the plurality of power transmitting coils 10. The first controller 12 controls the plurality of power transmitting circuits 11. The plurality of first measurement circuits 13 correspond one-to-one to the plurality of power transmitting circuits 11. The plurality of first measurement circuits 13 measure voltages and currents related to input power to corresponding ones of the plurality of power transmitting circuits 11. The power receiving terminal 2 includes a plurality of (two in the example of FIG. 1 ) power receiving coils 20, a plurality of (two in the example of FIG. 1 ) power receiving circuits 21, a DC output unit 24, a plurality of (two in the example of FIG. 1 ) switches 23, a second controller 22, and a plurality of (two in the example of FIG. 1 ) second measurement circuits 25. The plurality of power receiving coils 20 receive AC power from opposing power transmitting coils 10 among the plurality of power transmitting coils 10. The plurality of power receiving circuits 21 correspond one-to-one to the plurality of power receiving coils 20. The plurality of power receiving circuits 21 convert AC power received by corresponding power receiving coils 20 among the plurality of power receiving coils 20 into DC power. The DC output unit 24 includes a first DC output terminal 241 and a second DC output terminal 242. The first DC output terminal 241 is commonly connected to the high-potential side output terminals of the plurality of power receiving circuits 21. The second DC output terminal 242 is commonly connected to the low-potential side output terminals of the multiple power receiving circuits 21. The DC output unit 24 is connected to, for example, a battery (e.g., a lithium-ion battery) for storing electric energy, but is not limited to a battery. For example, a load that operates using electric energy may be connected. The multiple switches 23 correspond one-to-one to the multiple power receiving circuits 21. The multiple switches 23 are connected between the DC output unit 24 and corresponding power receiving circuits 21 among the multiple power receiving circuits 21. The second controller 22 controls the multiple switches 23. The multiple second measurement circuits 25 measure voltages and currents related to the output power of the multiple power receiving circuits 21.The first controller 12 calculates power efficiency based on the input power information and the output power information, and controls the plurality of power transmission circuits 11 based on the output power information and the power efficiency information. The second controller 22 controls the plurality of switches 23 based on control information for the plurality of switches 23 from the first controller 12.

[0013] According to the above configuration, it is possible to increase the DC power obtained at the power receiving terminal and improve the power efficiency.

[0014] In the wireless power feeding system 3, the power transmitter 1 further includes a first communication circuit 16. The power receiving terminal 2 further includes a second communication circuit 26. The power transmitter 1 further includes a power supply circuit 19.

[0015] The power transmitter 1 wirelessly supplies power to the power receiving terminal 2 placed on the power transmitter 1. The power receiving terminal 2 is, for example, a tablet terminal, a smartphone, or a notebook personal computer.

[0016] (2) Details Each component of the wireless power supply system 3 will be described in more detail below.

[0017] (2.1) Power Transmitter As shown in FIG. 1 , the power transmitter 1 has two power transmitting coils 10, two power transmitting circuits 11, two first measurement circuits 13, a first communication circuit 16, a power supply circuit 19, and a first controller 12.

[0018] Each of the two power transmitting coils 10 transmits power in a contactless manner to the opposing power receiving coil 20. The two power transmitting coils 10 include a first power transmitting coil 10a and a second power transmitting coil 10b.

[0019] The two power transmission circuits 11 correspond one-to-one to the two power transmission coils 10. In the power transmitter 1, the power transmission coil 10 corresponding to the power transmission circuit 11 is connected between two output terminals of each of the two power transmission circuits 11. The two power transmission circuits 11 include a first power transmission circuit 11a corresponding to the first power transmission coil 10a and a second power transmission circuit 11b corresponding to the second power transmission coil 10b.

[0020] Each of the two power transmission circuits 11 includes a DC-AC conversion circuit (inverter) 110 that converts DC power into AC power. As shown in FIG. 2 , the DC-AC conversion circuit 110 includes, for example, a capacitor C11, four switching elements Q11, Q12, Q13, and Q14, and a control circuit 115.

[0021] The capacitor C11 is connected between the output terminals of the power supply circuit 19. The four switching elements Q11, Q12, Q13, and Q14 are bridge-connected. In the power transmission circuit 11, a series circuit of the switching elements Q11 and Q12 and a series circuit of the switching elements Q13 and Q14 are connected in parallel to the capacitor C11. In the power transmission circuit 11, the power transmission coil 10 is connected between the connection point between the two switching elements Q11 and Q12 and the connection point between the two switching elements Q13 and Q14.

[0022] Each of the four switching elements Q11, Q12, Q13, and Q14 has a control terminal, a first main terminal, and a second main terminal. Each of the four switching elements Q11, Q12, Q13, and Q14 is, for example, a MOSFET. More specifically, each of the four switching elements Q11, Q12, Q13, and Q14 is a normally-off n-channel MOSFET. The control terminal, the first main terminal, and the second main terminal of each of the four switching elements Q11, Q12, Q13, and Q14 are a gate terminal, a drain terminal, and a source terminal, respectively. The control terminals of each of the four switching elements Q11, Q12, Q13, and Q14 are connected to the control circuit 115 via different gate drivers. In FIG. 2, the four diodes connected in anti-parallel to the four switching elements Q11 to Q14 in a one-to-one relationship are parasitic diodes of the n-channel MOSFETs that constitute each of the four switching elements Q11 to Q14, but they are not limited to parasitic diodes and may be external diodes.

[0023] Each of the two first measurement circuits 13 measures a voltage and a current associated with the input power of a corresponding one of the two power transmission circuits 11. In this embodiment, each of the two first measurement circuits 13 is provided between the power transmission circuit 11 corresponding to the first measurement circuit 13 and the power supply circuit 19. As shown in FIG. 3 , the first measurement circuit 13 includes a first voltage measurement circuit 131 that measures a voltage associated with the input power and a first current measurement circuit 132 that measures a current associated with the input power. The first voltage measurement circuit 131 includes, for example, a resistor divider circuit. The first current measurement circuit 132 includes, for example, a current detection resistor. As shown in FIG. 1 , the two first measurement circuits 13 include a first measurement circuit 13a and a first measurement circuit 13b. The first measurement circuit 13a measures a voltage and a current associated with the input power of the first power transmission circuit 11a. The first measurement circuit 13b measures a voltage and a current associated with the input power of the second power transmission circuit 11b. In the power transmitter 1 , the first controller 12 acquires the measured voltage and current values ​​from each of the two first measurement circuits 13 and calculates the value of the input power of each of the two power transmission circuits 11 .

[0024] The first communication circuit 16 is connected to the first controller 12. The first communication circuit 16 has a first antenna. The first communication circuit 16 performs wireless communication with the second communication circuit 26 of the power receiving terminal 2. The first communication circuit 16 transmits a first wireless signal WS1 including control information for the multiple switches 23 of the power receiving terminal 2 to the second communication circuit 26. The first communication circuit 16 also receives a second wireless signal WS2 from the second communication circuit 26 including information on the output power of the multiple power receiving circuits 21 of the power receiving terminal 2.

[0025] The power supply circuit 19 supplies a power supply voltage to, for example, the two first measurement circuits 13. The power supply circuit 19 includes, for example, a rectifier circuit connected to a commercial power supply and a step-down chopper circuit connected between output terminals of the rectifier circuit. The power supply circuit 19 also supplies a power supply voltage to the first controller 12. The power supply voltage output from the power supply circuit 19 is 5 V, but is not limited to 5 V and may be, for example, 10 V, 12 V, 15 V, or 24 V.

[0026] The first controller 12 controls the two power transmitting circuits 11. The first controller 12 calculates power efficiency based on information about the input power of the power transmitting circuit 11 and information about the output power of the power receiving circuit 21, and controls the multiple power transmitting circuits 11 based on information about the output power and power efficiency of the power receiving circuit 21. The first controller 12 calculates power efficiency using the formula: power efficiency = (output power / input power) x 100.

[0027] For example, when the total output power (total received power) based on the output power information is equal to or less than a threshold, the first controller 12 stops operation of some of the multiple power transmission circuits 11 and transmits control information to the second controller 22 to turn off the switches 23 connected between the DC output unit 24 and the power receiving circuits 21 corresponding to the some of the power transmission circuits 11 among the multiple power receiving circuits 21. The "total output power (total received power) based on the output power information" refers to the sum of the output power of each of the two power receiving circuits 21. In this embodiment, the two power receiving circuits 21 include a first power receiving circuit 21a and a second power receiving circuit 21b, and the total output power is the sum of the output power of the first power receiving circuit 21a and the output power of the second power receiving circuit 21b. The two second measurement circuits 25 include a second measurement circuit 25a corresponding to the first power receiving circuit 21a and a second measurement circuit 25b corresponding to the second power receiving circuit 21b. The second measurement circuit 25a measures the voltage and current associated with the output power of the first power receiving circuit 21a, and the second measurement circuit 25b measures the voltage and current associated with the output power of the second power receiving circuit 21b.

[0028] The first controller 12 determines, based on the information on power efficiency, which of the multiple power transmission circuits 11 to stop and which of the multiple switches 23 to turn off. In this embodiment, the first controller 12 is configured to be able to switch the operation mode of the power transmitter 1 between a first power transmission mode and a second power transmission mode. The first power transmission mode is a power transmission mode in which multiple (two in the example of FIG. 1 ) coil pairs are simultaneously used between the power transmitter 1 and the power receiving terminal 2 to transmit power for each coil pair, and the output power of multiple (two in the example of FIG. 1 ) power receiving circuits 21 is combined. A "coil pair" refers to a pair of a power transmission coil 10 and a power receiving coil 20 that face each other. Therefore, the multiple coil pairs include, for example, a coil pair of a first power transmission coil 10a and a first power receiving coil 20a (hereinafter also referred to as a first pair) and a coil pair of a second power transmission coil 10b and a second power receiving coil 20b (hereinafter also referred to as a second pair). The second power transmission mode is a power transmission mode (second power transmission mode) in which power is transmitted between the power transmitter 1 and the power receiving terminal 2 or the power receiving terminal 2R (see FIG. 7 ) using one coil pair. The power receiving terminal 2R differs from the power receiving terminal 2 in that it has one power receiving coil 20. In the first power transmission mode, the power transmitter 1 can transmit greater power than in the second power transmission mode.

[0029] The first controller 12 includes a computer system. The computer system is primarily composed of a processor and memory as hardware. The processor executes a program stored in the computer system's memory to realize the functions of the first controller 12 in the present disclosure. The program may be pre-stored in the computer system's memory, provided via a telecommunications line, or provided on a non-transitory recording medium readable by the computer system, such as a memory card, optical disk, or hard disk drive. The processor of the computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). The integrated circuits, such as ICs and LSIs, are referred to by different names depending on the degree of integration, and include integrated circuits called system LSIs, very large-scale integrations (VLSIs), or ultra-large-scale integrations (ULSIs). Furthermore, field-programmable gate arrays (FPGAs), which are programmed after the LSI is manufactured, or logic devices capable of reconfiguring the connections within the LSI or reconfiguring the circuit partitions within the LSI, can also be used as processors. The electronic circuits may be integrated into one chip or distributed across multiple chips. The chips may be integrated into one device or distributed across multiple devices. The computer system referred to here includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller is also composed of one or more electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

[0030] 5 and 6, the power transmitter 1 further includes a housing 40, a moving system 50, and a position detection device 60. The housing 40 houses two power transmitting coils 10, two power transmitting circuits 11, a first controller 12, a first communication circuit 16, a power supply circuit 19, and the moving system 50. Note that the two power transmitting circuits 11, the first controller 12, the first communication circuit 16, and the power supply circuit 19 are not shown in FIGS. 5 and 6.

[0031] The housing 40 is in the shape of a rectangular box with an opening on one side.

[0032] 5 and 6 , an orthogonal coordinate system having three mutually orthogonal axes, i.e., an X-axis, a Y-axis, and a Z-axis, will be defined below, and the axis along the winding axis direction of the two power transmission coils 10 will be particularly referred to as the "Z-axis." The X-axis, Y-axis, and Z-axis are all imaginary axes, and the arrows indicating "X," "Y," and "Z" in the drawings are merely shown for the purpose of explanation and do not have any physical substance.

[0033] Each of the two power transmitting coils 10 is a spiral planar coil. When viewed in the Z-axis direction, the outer shape of each of the two power transmitting coils 10 is, for example, circular.

[0034] The movement system 50 is configured to independently move the two power transmitting coils 10. The two power transmitting coils 10 include a first power transmitting coil 10a and a second power transmitting coil 10b. The movement system 50 can independently move the first power transmitting coil 10a and the second power transmitting coil 10b in the X-axis direction and the Y-axis direction, respectively.

[0035] The movement system 50 has two bases 51 , two X-axis rails 52 , two Y-axis rails 53 , two X-axis drive units 54 , two Y-axis drive units 55 , and four support bases 56 .

[0036] The two pedestals 51 correspond one-to-one to the two power transmitting coils 10. Each of the two pedestals 51 holds a corresponding one of the two power transmitting coils 10. When viewed from the Z-axis direction, the outer shape of each of the two pedestals 51 is, for example, a quadrangle.

[0037] Each of the two X-axis rails 52 is disposed along the X-axis direction. Each of the two X-axis rails 52 has an elongated shape such that the length in the X-axis direction is longer than the length in the Y-axis direction. The two X-axis rails 52 (first X-axis rail 52a, second X-axis rail 52b) are spaced apart from each other in the Y-axis direction.

[0038] Each of the two Y-axis rails 53 is arranged along the Y-axis direction. Each of the two Y-axis rails 53 has an elongated shape such that the length in the Y-axis direction is longer than the length in the X-axis direction. The two Y-axis rails 53 are spaced apart from each other in the X-axis direction. Each of the two Y-axis rails 53 is movably connected to the two X-axis rails 52.

[0039] The two X-axis drive units 54 correspond one-to-one to the two Y-axis rails 53. In the movement system 50, the two X-axis drive units 54 include a first X-axis drive unit 54a and a second X-axis drive unit 54b, and the two Y-axis rails 53 include a first Y-axis rail 53a corresponding to the first X-axis drive unit 54a and a second Y-axis rail 53b corresponding to the second X-axis drive unit 54b. The first X-axis drive unit 54a is held by the first Y-axis rail 53a. The second X-axis drive unit 54b is held by the second Y-axis rail 53b. The first X-axis drive unit 54a moves the first Y-axis rail 53a along the two X-axis rails 52. The second X-axis drive unit 54b moves the second Y-axis rail 53b along the two X-axis rails 52.

[0040] In the movement system 50, the two Y-axis drive units 55 include a first Y-axis drive unit 55a and a second Y-axis drive unit 55b. The first Y-axis drive unit 55a moves the base 51, which is movably connected to the first Y-axis rail 53a, along the first Y-axis rail 53a. The second Y-axis drive unit 55b moves the base 51, which is movably connected to the second Y-axis rail 53b, along the second Y-axis rail 53b.

[0041] The movement system 50 of this embodiment has multiple rack-and-pinion mechanisms. In this embodiment, each of the two X-axis rails 52 is a rack having multiple teeth aligned in the X-axis direction. Each of the two X-axis rails 52 is supported by two support bases 56 fixed to the housing 40.

[0042] Each of the two X-axis drive units 54 corresponds one-to-one to the two Y-axis rails 53 and is held by the corresponding Y-axis rail 53. Each of the two X-axis drive units 54 includes a pinion (gear) 542 that meshes with a rack that constitutes the X-axis rail 52, and a motor 541 that is held by the Y-axis rail 53 and rotates the pinion 542. The pinion 542 is connected to the output shaft of the motor 541.

[0043] In this embodiment, each of the two Y-axis rails 53 has a rack 531 having a plurality of teeth aligned in the Y-axis direction, and a slider 532 adjacent to the rack 531. The slider 532 holds the base 51 in a slidable manner.

[0044] Each of the two Y-axis drive units 55 includes a pinion (gear) 552 that meshes with the rack 531, and a motor 551 that is held by the base 51 and rotates the pinion 552. The pinion 552 is connected to the output shaft of the motor 551.

[0045] The movement system 50 is controlled by, for example, a first controller 12. In the movement system 50, the motor 541 of the first X-axis drive unit 54a, the motor 541 of the second X-axis drive unit 54b, the motor 551 of the first Y-axis drive unit 55a, and the motor 551 of the second Y-axis drive unit 55b are independently controlled by the first controller 12.

[0046] The movement system 50 is not limited to the above example as long as it can move a plurality of (two) power transmission coils 10 independently.

[0047] The position detection device 60 is a device for detecting the position of the power receiving coil 20 of the power receiving terminal 2 arranged on the power transmitter 1. As shown in Fig. 5 , the position detection device 60 includes a printed circuit board 63 having a plurality of first search coils 61 (six in the example of Fig. 5 ) and a plurality of second search coils 62 (four in the example of Fig. 5 ). The printed circuit board 63 is in the shape of a rectangular plate. The position detection device 60 is attached to the housing 40 so as to close the opening of the housing 40.

[0048] Each of the multiple first search coils 61 has a rectangular shape. The longitudinal direction of each of the multiple first search coils 61 is along the Y-axis direction. The multiple first search coils 61 are arranged side by side at equal intervals in the X-axis direction.

[0049] Each of the second search coils 62 has a rectangular shape. The longitudinal direction of each of the second search coils 62 is along the X-axis direction. The second search coils 62 are arranged side by side at equal intervals in the Y-axis direction.

[0050] The printed circuit board 63 is a double-sided or multilayer printed circuit board, and a first surface on which the multiple first search coils 61 are arranged and a second surface on which the multiple second search coils 62 are arranged are spaced apart from each other in the thickness direction of the printed circuit board 63. The thickness direction of the printed circuit board 63 is along the Z-axis direction. In the position detection device 60, the multiple first search coils 61 and the multiple second search coils 62 intersect (orthogonally intersect) with each other when viewed from the Z-axis direction. The multiple first search coils 61 and the multiple second search coils 62 are connected to, for example, the first controller 12. When the first surface on which the multiple first search coils 61 are arranged is the first main surface of the printed circuit board 63, the multiple first search coils 61 are covered with a first resist layer (not shown). When the second surface on which the multiple second search coils 62 are arranged is the second main surface of the printed circuit board 63, the multiple second search coils 62 are covered with a second resist layer (not shown).

[0051] The first controller 12 supplies pulse signals to the plurality of first search coils 61 and the plurality of second search coils 62 .

[0052] When the power receiving terminal 2 is placed on the power transmitter 1, each of the two power receiving coils 20 of the power receiving terminal 2 is excited by a pulse signal and outputs an echo signal to the opposing first search coil 61 of the multiple first search coils 61. The first search coil 61 outputs the received echo signal to the first controller 12. The first controller 12 calculates the X coordinate of the power receiving coil 20 based on pre-stored position information of each of the multiple first search coils 61 and the level of the echo signal. For example, the first controller 12 determines the X coordinate of the first search coil 61 of the multiple first search coils 61, whose echo signal level is equal to or greater than a predetermined value and is a local maximum, as the X coordinate of the power receiving coil 20.

[0053] Furthermore, when the power receiving terminal 2 is placed on the power transmitter 1, each of the two power receiving coils 20 of the power receiving terminal 2 is excited by a pulse signal and outputs an echo signal to the opposing second search coil 62 of the multiple second search coils 62. The second search coil 62 receives the echo signal and outputs it to the first controller 12. The first controller 12 calculates the Y coordinate of the power receiving coil 20 based on pre-stored position information of each of the multiple second search coils 62 and the level of the echo signal. For example, the first controller 12 determines the Y coordinate of the second search coil 62 of the multiple second search coils 62 whose echo signal level is equal to or greater than a predetermined value and is maximum as the Y coordinate of the power receiving coil 20.

[0054] 7, the power transmitter 1 is configured to be able to transmit power to two power receiving terminals 2R each having only one power receiving coil 20. With regard to the power receiving terminal 2R, components similar to those of the power receiving terminal 2 are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0055] (2.2) Power Receiving Terminal As shown in FIG. 1 , the power receiving terminal 2 has two power receiving coils 20, two power receiving circuits 21, a DC output unit 24, two switches 23, a second controller 22, and two second measurement circuits 25.

[0056] Each of the multiple (two in the example of FIG. 1 ) power receiving coils 20 receives AC power from an opposing one of the multiple (two in the example of FIG. 1 ) power transmitting coils 10 by electromagnetic induction or magnetic field resonance. Each of the two power receiving coils 20 is a spiral planar coil. The outer shape of each of the two power receiving coils 20 is, for example, circular. The two power receiving coils 20 include a first power receiving coil 20a and a second power receiving coil 20b.

[0057] The two power receiving circuits 21 correspond one-to-one to the two power receiving coils 20. In the power receiving terminal 2, the power receiving coil 20 corresponding to the power receiving circuit 21 is connected between the two input terminals of each of the two power receiving circuits 21. The two power receiving circuits 21 include a first power receiving circuit 21a corresponding to the first power receiving coil 20a and a second power receiving circuit 21b corresponding to the second power receiving coil 20b.

[0058] Each of the plurality of power receiving circuits 21 includes, for example, a rectifier circuit 211, as shown in Fig. 4. In the example of Fig. 4, the rectifier circuit 211 includes four switching elements Q21, Q22, Q23, and Q24, a capacitor C21, and a control circuit 215.

[0059] The four switching elements Q21, Q22, Q23, and Q24 are bridge-connected. In the rectifier circuit 211, a series circuit of the switching elements Q21 and Q22 and a series circuit of the switching elements Q23 and Q24 are connected in parallel. In the rectifier circuit 211, the receiving coil 20 is connected between the connection point between the two switching elements Q21 and Q22 and the connection point between the two switching elements Q23 and Q24. In the rectifier circuit 211, the capacitor C21 is connected in parallel with the series circuit of the switching elements Q23 and Q24 and the series circuit of the switching elements Q21 and Q22.

[0060] Each of the four switching elements Q21, Q22, Q23, and Q24 has a control terminal, a first main terminal, and a second main terminal. Each of the four switching elements Q21, Q22, Q23, and Q24 is, for example, a MOSFET. More specifically, each of the four switching elements Q21, Q22, Q23, and Q24 is a normally-off n-channel MOSFET. The control terminal, the first main terminal, and the second main terminal of each of the four switching elements Q21, Q22, Q23, and Q24 are a gate terminal, a drain terminal, and a source terminal, respectively. The control terminals of each of the four switching elements Q21, Q22, Q23, and Q24 are connected to the control circuit 215 via different gate drivers. In FIG. 4, the four diodes connected in anti-parallel to the four switching elements Q21 to Q24 in a one-to-one relationship are parasitic diodes of the n-channel MOSFETs that constitute each of the four switching elements Q21 to Q24, but they are not limited to parasitic diodes and may be external diodes.

[0061] The control circuit 215 controls the four switching elements Q21, Q22, Q23, and Q24. In this embodiment, the control circuit 215 controls the four switching elements Q21, Q22, Q23, and Q24 so that the rectifier circuit 211 operates as a synchronous rectifier circuit.

[0062] The multiple switches 23 include a first switch 23a connected between the first power receiving circuit 21a and the DC output unit 24 and a second switch 23b connected between the second power receiving circuit 21b and the DC output unit 24. The second controller 22 independently controls the multiple switches 23. In this embodiment, each of the two switches 23 is a double-pole switch. Therefore, when in an on state, each of the two switches 23 establishes a conductive state between the high-potential output terminal of the power receiving circuit 21 and the first DC output terminal 241, and a conductive state between the low-potential output terminal of the power receiving circuit 21 and the second DC output terminal 242. When in an off state, each of the two switches 23 establishes a disconnected state (open state) between the high-potential output terminal of the power receiving circuit 21 and the first DC output terminal 241, and a disconnected state (open state) between the low-potential output terminal of the power receiving circuit 21 and the second DC output terminal 242.

[0063] Each of the two second measurement circuits 25 measures a voltage and a current related to the output power of a corresponding one of the two power receiving circuits 21. In this embodiment, each of the two second measurement circuits 25 is provided between the power receiving circuit 21 corresponding to the second measurement circuit 25 and the switch 23. The second measurement circuit 25 includes a second voltage measurement circuit that measures a voltage (DC voltage) related to the output power and a second current measurement circuit that measures a current (DC current) related to the output power. The second voltage measurement circuit includes, for example, a resistive voltage divider circuit. The second current measurement circuit includes, for example, a current detection resistor. In the power receiving terminal 2, the second controller 22 acquires the measured voltage and current values ​​from each of the two second measurement circuits 25 and calculates the value of the output power of each of the two power receiving circuits 21.

[0064] The second communication circuit 26 is connected to the second controller 22. The second communication circuit 26 has a second antenna. The second communication circuit 26 performs wireless communication with the first communication circuit 16 of the power transmitter 1. The second communication circuit 26 transmits a second wireless signal WS2 containing information about the output power of the power receiving circuit 21 to the first communication circuit 16. The second communication circuit 26 also receives a first wireless signal WS1 containing control information for the two switches 23 from the first communication circuit 16. In FIG. 1 , the dashed arrow pointing from the first communication circuit 16 to the second communication circuit 26 indicates the first wireless signal WS1 containing the control information for the two switches 23. In FIG. 1 , the dashed arrow pointing from the second communication circuit 26 to the first communication circuit 16 indicates the second wireless signal WS2 containing information about the output power of the power receiving circuit 21 of the power receiving terminal 2.

[0065] The second controller 22 causes the second communication circuit 26 to transmit information about the output power of the power receiving circuits 21 of the power receiving terminal 2 to the first communication circuit 16. The information about the output power includes information about the total output power (total received power) of the output power of each of the two power receiving circuits 21, which the second controller 22 has obtained by acquiring voltage measurement values ​​and current measurement values ​​from each of the two second measurement circuits 25.

[0066] The second controller 22 independently controls each of the plurality of switches 23 based on control information for the plurality of switches 23 from the first controller 12 .

[0067] The second controller 22 includes a computer system. The computer system is primarily composed of a processor and memory as hardware. The processor executes a program stored in the computer system's memory to realize the functions of the second controller 22 in the present disclosure. The program may be pre-recorded in the computer system's memory, provided via a telecommunications line, or provided on a non-transitory recording medium readable by the computer system, such as a memory card, optical disk, or hard disk drive. The processor of the computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). The IC or LSI referred to here is referred to by different names depending on the degree of integration, and includes integrated circuits called system LSI, very large scale integration (VLSI), or ultra large scale integration (ULSI). Furthermore, a field-programmable gate array (FPGA), which is programmed after the LSI is manufactured, or a logic device capable of reconfiguring the connections within the LSI or reconfiguring the circuit partitions within the LSI, can also be used as a processor. The electronic circuits may be integrated into one chip or distributed across multiple chips. The chips may be integrated into one device or distributed across multiple devices. The computer system referred to here includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller is also composed of one or more electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

[0068] The power receiving terminal 2 has the above-mentioned battery (not shown) connected to the DC output unit 24, and operates using the battery as a power source.

[0069] (3) Operation of Wireless Power Supply System An example of the operation of the power transmitter 1 will be described below with reference to FIGS. 8 and 9. FIG.

[0070] When the first controller 12 detects the power receiving coil 20 using the position detection device 60 (step S1: Yes), it determines whether the number of power receiving coils 20 is one (step S2). If the number of power receiving coils 20 is one (step S2: Yes), the first controller 12 switches the operation mode to the second power transmission mode (step S3). Note that the number of power receiving coils 20 is one when, for example, only one of the two power receiving terminals 2R shown in FIG. 7 (for example, the left power receiving terminal 2R in FIG. 7) is placed on the power transmitter 1.

[0071] After step S3, the first controller 12 identifies the position (X coordinate and Y coordinate) of the power receiving coil 20 (step S4), moves the power transmitting coil 10 (e.g., the first power transmitting coil 10a) that is closest to the power receiving coil 20 of the power receiving terminal 2R using the mobile system 50 to a position facing the power receiving coil 20 of the power receiving terminal 2R, and starts power transmission from the power transmitting coil 10 to the power receiving coil 20 (step S5). After step S5, if the first controller 12 detects another power receiving coil 20 (step S6: Yes), it identifies the position of the other power receiving coil 20 (step S7), moves the remaining power transmitting coil 10 (e.g., the second power transmitting coil 10b) of the two power transmitting coils 10 to a position facing the other power receiving coil 20, and starts power transmission from the power transmitting coil 10 to the power receiving coil 20 (step S8). After step S8, when power transmission to all (e.g., two) power receiving coils 20 is completed (step S9), the first controller 12 ends the operation of the power transmitting circuit 11. The other power receiving coil 20 is, for example, the power receiving coil 20 included in the power receiving terminal 2R on the right side of the power receiving terminals 2R shown in FIG.

[0072] Furthermore, if the number of power receiving coils 20 detected in step S1 is multiple (for example, two) (step S2: No), the first controller 12 determines whether the number of power receiving terminals is one (step S10). If the number of power receiving terminals is one (step S10: Yes), the first controller 12 switches the operation mode to the first power transmission mode (step S11). On the other hand, if the number of power receiving terminals is not one (step S10: No), the first controller 12 proceeds to step S3.

[0073] After step S11, the first controller 12 identifies the positions of all (for example, two) power receiving coils 20 (step S12). Then, the first controller 12 moves the two power transmitting coils 10 by the movement system 50 so that they face the two power receiving coils 20 in a one-to-one relationship (step S13).

[0074] After step S13, the first controller 12 starts power transmission in the first power transmission mode (step S21). Thereafter, the first controller 12 receives information on the total received power (DC power obtained by the power receiving terminal 2) from the power receiving terminal 2 (step S22). The information on the received power of the power receiving terminal 2 received in step S22 includes information on the sum of the output power of each of the two power receiving circuits 21 (total received power). The output power of each of the two power receiving circuits 21 is an output power value calculated by the second controller 22 by acquiring measured voltage values ​​and measured current values ​​from each of the two second measurement circuits 25.

[0075] After step S22, the first controller 12 determines whether the total received power is equal to or less than a threshold value (step S23). The threshold value is, for example, the value of the maximum received power for the pair of the first power transmitting coil 10 a and the first power receiving coil 20 a. The value of the maximum received power is stored in advance in the memory of the first controller 12 or the memory of the second controller 22.

[0076] If the total received power is greater than the threshold value in step S23 (step S23: No), the first controller 12 continues power transmission in the first power transmission mode (step S21).

[0077] Furthermore, if the total received power is equal to or less than the threshold value in step S23 (step S23: Yes), the first controller 12 switches the power transmission mode from the first power transmission mode to the second power transmission mode (step S24). After step S24, the first controller 12 calculates the power efficiency for each of the multiple coil pairs (step S25). A "coil pair" refers to a pair of a power transmitting coil 10 and a power receiving coil 20 that face each other. Therefore, the multiple coil pairs include, for example, a coil pair of a first power transmitting coil 10a and a first power receiving coil 20a (hereinafter also referred to as a first pair) and a coil pair of a second power transmitting coil 10b and a second power receiving coil 20b (hereinafter also referred to as a second pair).

[0078] The first controller 12 compares the power efficiencies of the multiple coil pairs, and if the power efficiency of the first pair is greater than the power efficiency of the second pair (step S26: Yes), stops power transmission from the second power transmitting coil 10b and increases the power of the first power transmitting coil 10a to a power transmitting level that provides the maximum power received by the first power receiving coil 20a (step S27). After step S27, the first controller 12 causes the first communication circuit 16 to transmit control information for the two switches 23, such control information for switching the second switch 23b from a conductive state to a disconnected state and for maintaining the first switch 23a in the conductive state, to the second communication circuit 26 (step S28). When the second controller 22 in the power receiving terminal 2 receives the control information via the second communication circuit 26, it switches the second switch 23b from a conductive state (see FIG. 10 ) to a disconnected state and maintains the first switch 23a in the conductive state (see FIG. 11 ). 10 and 11, the outline arrows schematically indicate the direction of power transmission from the power transmission coil 10 to the power receiving coil 20.

[0079] After step S28 , when the first controller 12 receives an instruction to end power transmission from the power receiving terminal 2 (step S29 ), the first controller 12 ends power transmission to the power receiving terminal 2 .

[0080] Furthermore, if the power efficiency of the first pair is equal to or lower than the power efficiency of the second pair at step S26 (step S26: No), the first controller 12 stops power transmission from the first power transmitting coil 10a and increases the power of the second power transmitting coil 10b to a power transmitting level at which the maximum received power of the second power receiving coil 20b is obtained (step S31). After step S31, the first controller 12 causes the first communication circuit 16 to transmit, as control information for the two switches 23, control information for switching the first switch 23a from a conductive state to a disconnected state and for maintaining the second switch 23b in a conductive state to the second communication circuit 26 (step S32).

[0081] After step S32, when the first controller 12 receives an instruction to end power transmission from the power receiving terminal 2 (step S33), the first controller 12 ends power transmission to the power receiving terminal 2. Note that the instruction to end power transmission from the power receiving terminal 2 to the power transmitter 1 is given, for example, when charging of the battery in the power receiving terminal 2 is completed and power transmission from the power transmitter 1 is no longer necessary. If a load instead of a battery is connected to the DC output unit 24, the instruction to end power transmission from the power receiving terminal 2 to the power transmitter 1 is given, for example, when operation of the load is no longer necessary.

[0082] (4) Advantages The wireless power feeding system 3 according to the first embodiment includes a power transmitter 1 and a power receiving terminal 2. The power transmitter 1 includes a plurality of power transmitting coils 10, a plurality of power transmitting circuits 11, a first controller 12, and a plurality of first measurement circuits 13. The power receiving terminal 2 includes a plurality of power receiving coils 20, a plurality of power receiving circuits 21, a DC output unit 24, a plurality of switches 23, a second controller 22, and a plurality of second measurement circuits 25. The plurality of switches 23 are connected between corresponding ones of the plurality of power receiving circuits 21 and the DC output unit 24. The plurality of second measurement circuits 25 measure voltages and currents related to the output power of the plurality of power receiving circuits 21. The first controller 12 calculates power efficiency based on information about the input power of the power transmitting circuit 11 and information about the output power of the power receiving circuit 21, and controls the plurality of power transmitting circuits 11 based on information about the output power of the power receiving circuit 21 and information about the power efficiency. The second controller 22 controls the switches 23 based on control information for the switches 23 from the first controller 12 .

[0083] The above configuration enables the power receiving terminal 2 to obtain higher DC power and improve power efficiency. More specifically, in the wireless power feeding system 3 according to the first embodiment, the power transmitter 1 has two power transmitting coils 10, the power receiving terminal 2 has two power receiving coils 20, and the DC powers can be combined in the power receiving terminal 2, thereby enabling the power receiving terminal 2 to obtain higher DC power. Furthermore, in wireless power feeding systems, power efficiency tends to decrease as the output power of the power receiving circuit decreases. However, in the wireless power feeding system 3 according to the first embodiment, the first controller 12 calculates power efficiency based on information about the input power of the power transmitting circuit 11 and information about the output power of the power receiving circuit 21, and controls the multiple power transmitting circuits 11 based on the information about the output power of the power receiving circuit 21 and the information about the power efficiency, and the second controller 22 controls the multiple switches 23 based on control information for the multiple switches 23 from the first controller 12. This enables the wireless power feeding system 3 to improve power efficiency.

[0084] Moreover, in the wireless power feeding system 3 according to the first embodiment, the power transmitter 1 further includes a first communication circuit 16, and the power receiving terminal 2 further includes a second communication circuit 26. The second controller 22 causes the second communication circuit 26 to transmit a second wireless signal WS2 including information about output power to the first communication circuit 16, and acquires control information included in the first wireless signal WS1 transmitted from the first communication circuit 16 and received by the second communication circuit 26. The first controller 12 acquires the information about output power included in the second wireless signal WS2 received by the first communication circuit 16, and causes the first communication circuit 16 to transmit the first wireless signal WS1 including the control information to the second communication circuit 26.

[0085] According to the above configuration, it is possible to improve the communication performance between the power transmitter 1 and the power receiving terminal 2 .

[0086] Furthermore, in the wireless power supply system 3 of embodiment 1, when the total received power based on the output power information is equal to or less than a threshold value, the first controller 12 stops the operation of some of the multiple power transmission circuits 11, and transmits to the second controller 22, as control information, off control information for turning off the switches 23 connected between the DC output unit 24 and the power receiving circuits 21 corresponding to the some of the power transmission circuits 11 among the multiple power receiving circuits 21.

[0087] According to the above configuration, it is possible to improve power efficiency when the received power required by the power receiving terminal 2 (the output power required by the DC output unit 24) decreases and the total received power falls below a threshold value.

[0088] The power receiving terminal 2 according to the first embodiment includes a plurality of power receiving coils 20, a plurality of power receiving circuits 21, a DC output unit 24, a plurality of switches 23, a second controller 22, and a plurality of second measurement circuits 25. The power receiving circuits 21 correspond one-to-one to the power receiving coils 20 and convert AC power received by a corresponding power receiving coil 20 among the plurality of power receiving coils 20 into DC power. The DC output unit 24 includes a first DC output terminal 241 to which high-potential output terminals of the power receiving circuits 21 are commonly connected and a second DC output terminal 242 to which low-potential output terminals of the power receiving circuits 21 are commonly connected. The DC output unit 24 is connected to, for example, a battery (e.g., a lithium-ion battery) for storing electrical energy. However, the connection is not limited to a battery, and may also be to a load that operates using electrical energy, for example. The multiple switches 23 correspond one-to-one to the multiple power receiving circuits 21, and are connected between a corresponding one of the multiple power receiving circuits 21 and the DC output unit 24. The second controller 22 controls the multiple switches 23. The multiple second measurement circuits 25 measure voltages and currents related to the output power of the multiple power receiving circuits 21. The second controller 22 controls the multiple switches 23 based on control information of the multiple switches 23.

[0089] According to the above configuration, it is possible to improve the power efficiency when receiving power from the power transmitter 1 .

[0090] Furthermore, the power transmitter 1 according to the first embodiment can improve the power efficiency when transmitting power to the power receiving terminal 2 .

[0091] According to the above configuration, it is possible to improve power efficiency.

[0092] (5) Modifications The rectifier circuit 211 of the power receiving circuit 21 may include, for example, a diode bridge in which four diodes D21, D22, D23, and D24 are bridge-connected, and a capacitor C22 connected between two output terminals of the diode bridge, as shown in Fig. 12. The power receiving coil 20 is connected between two input terminals of the diode bridge.

[0093] Furthermore, the rectifier circuit 211 of the power receiving circuit 21 may be configured to include a series circuit of a diode D25 and a capacitor C23 connected to the power receiving coil 20, as shown in FIG. 13, for example.

[0094] 14, the wireless power feeding system 3 may be configured to transmit a wireless signal WS3 including information about the number of power receiving coils 20 from the second communication circuit 26 to the first communication circuit 16. In this case, step S10 is unnecessary in the operation (control algorithm) of the first controller 12 described in the flowcharts of FIGS. 8 and 9, simplifying the control algorithm and shortening the time until charging of the battery of the power receiving terminal 2 starts. Also, the power receiving terminal 2R shown in FIG. 7 may be configured to wirelessly notify the first communication circuit 16 of the number of power receiving coils 20 from the second communication circuit 26.

[0095] (Embodiment 2) Hereinafter, a wireless power feeding system 3A according to embodiment 2 will be described with reference to Fig. 15. Regarding the wireless power feeding system 3A according to embodiment 2, components similar to those of the wireless power feeding system 3 according to embodiment 1 are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0096] (1) Configuration As shown in FIG. 15 , the wireless power feeding system 3A differs from the wireless power feeding system 3 according to the first embodiment in that it includes a power receiving terminal 2A instead of the power receiving terminal 2 of the wireless power feeding system 3 according to the first embodiment.

[0097] The power receiving terminal 2A differs from the power receiving terminal 2 according to embodiment 1 in that it includes one second measurement circuit 25A instead of the two second measurement circuits 25 of the power receiving terminal 2 according to embodiment 1. Note that components of the power receiving terminal 2A that are the same as those of the power receiving terminal 2 are denoted by the same reference numerals and descriptions thereof will be omitted as appropriate.

[0098] Similar to the second measurement circuit 25 of the first embodiment, the second measurement circuit 25A includes a voltage measurement circuit and a current measurement circuit. The second measurement circuit 25A is provided between the two switches 23 and the DC output unit 24, and measures the voltage and current of the DC power obtained by combining the output power of the first power receiving circuit 21a and the output power of the second power receiving circuit 21b. More specifically, the voltage measurement circuit in the second measurement circuit 25A measures the voltage between the first DC output terminal 241 and the second DC output terminal 242, and the current measurement circuit in the second measurement circuit 25A measures the current flowing through the first DC output terminal 241.

[0099] In the power receiving terminal 2A, the second controller 22 acquires the measured voltage and current values ​​from the second measurement circuit 25A and calculates the total output power of the two power receiving circuits 21.

[0100] The second controller 22 causes information about the received power of the power receiving terminal 2A to be transmitted from the second communication circuit 26 to the first communication circuit 16. The information about the received power includes information about the total output power (total received power) of the two power receiving circuits 21, which the second controller 22 has calculated by acquiring measured voltage values ​​and measured current values ​​from the second measurement circuit 25A.

[0101] (2) Advantages Like the wireless power feeding system 3 according to the first embodiment, the wireless power feeding system 3A according to the second embodiment can increase the DC power obtained at the power receiving terminal 2A and improve the power efficiency.

[0102] In addition, the power receiving terminal 2A of embodiment 2 has one second measurement circuit 25A instead of the two second measurement circuits 25 of the power receiving terminal 2 of embodiment 1, which makes it possible to reduce costs and size.

[0103] (Embodiment 3) A wireless power feeding system 3B according to embodiment 3 will be described below with reference to Fig. 16 to Fig. 18. Regarding the wireless power feeding system 3B according to embodiment 3, components similar to those of the wireless power feeding system 3 according to embodiment 1 are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0104] (1) Configuration The wireless power feeding system 3B includes a power transmitter 1B and a power receiving terminal 2B instead of the power transmitter 1 and the power receiving terminal 2 of the wireless power feeding system 3 according to the first embodiment. Note that, for the power transmitter 1B, components similar to those of the power transmitter 1 are denoted by the same reference numerals and descriptions thereof are omitted as appropriate. For the power receiving terminal 2B, components similar to those of the power receiving terminal 2 are denoted by the same reference numerals and descriptions thereof are omitted as appropriate.

[0105] 16 , the wireless power supply system 3B differs from the wireless power supply system 3 according to the first embodiment in that wireless communication is performed between the first power transmission circuit 11a and the first power receiving circuit 21a and between the second power transmission circuit 11b and the second power receiving circuit 21b. In FIG. 16 , the dashed arrow pointing from the first power transmission circuit 11a to the first power receiving circuit 21a indicates a first wireless signal WS1 containing control information for the first switch 23a. In FIG. 16 , the dashed arrow pointing from the first power receiving circuit 21a to the first power transmission circuit 11a indicates a second wireless signal WS2 containing information about the output power of the first power receiving circuit 21a. In FIG. 16 , the dashed arrow pointing from the second power transmission circuit 11b to the second power receiving circuit 21b indicates a first wireless signal WS1 containing control information for the second switch 23b. In addition, in FIG. 16, the dashed arrow pointing from the second power receiving circuit 21b to the second power transmitting circuit 11b indicates the second wireless signal WS2 that includes information about the output power of the second power receiving circuit 21b.

[0106] In the wireless power supply system 3B, each of the two power transmitting circuits 11 includes a DC-AC conversion circuit 110 and a first communication circuit 16, as shown in FIG. 17, and each of the two power receiving circuits 21 includes a rectifier circuit 211 and a second communication circuit 26, as shown in FIG. 18.

[0107] (2) Advantages Like the wireless power feeding system 3 according to the first embodiment, the wireless power feeding system 3B according to the third embodiment can increase the DC power obtained at the power receiving terminal 2B and improve the power efficiency.

[0108] In addition, the wireless power supply system 3B of embodiment 3 is capable of performing wireless communication between the first power transmission circuit 11a and the first power receiving circuit 21a, and between the second power transmission circuit 11b and the second power receiving circuit 21b, so that when the first controller 12 is in the second power transmission mode, communication is possible for each power receiving circuit 21.

[0109] (Fourth embodiment) A wireless power feeding system 3C according to a fourth embodiment will be described below with reference to Fig. 19 to Fig. 21. Regarding the wireless power feeding system 3C according to the fourth embodiment, the same components as those in the wireless power feeding system 3 according to the first embodiment will be denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0110] (1) Configuration The wireless power feeding system 3C includes a power transmitter 1C and a power receiving terminal 2C instead of the power transmitter 1 and the power receiving terminal 2 of the wireless power feeding system 3 according to the first embodiment. Note that, for the power transmitter 1C, components similar to those of the power transmitter 1 are denoted by the same reference numerals and descriptions thereof are omitted as appropriate. For the power receiving terminal 2C, components similar to those of the power receiving terminal 2 are denoted by the same reference numerals and descriptions thereof are omitted as appropriate.

[0111] 19 , the wireless power feeding system 3C differs from the wireless power feeding system 3 according to the first embodiment in that wireless communication is performed between the first power transmitting circuit 11a and the first power receiving circuit 21a and between the second power transmitting circuit 11b and the second power receiving circuit 21b. Note that in Fig. 19 , the dashed arrow pointing from the first power transmitting coil 10a connected to the first power receiving circuit 21a to the first power receiving coil 20a connected to the first power receiving circuit 21a indicates a first wireless signal WS1 containing control information for the first switch 23a. Also, in Fig. 19 , the dashed arrow pointing from the first power receiving coil 20a to the first power transmitting coil 10a indicates a second wireless signal WS2 containing information about the output power of the first power receiving circuit 21a. 19, a dashed arrow pointing from the second power transmitting coil 10b connected to the second power transmitting circuit 11b to the second power receiving coil 20b connected to the second power receiving circuit 21b indicates a first wireless signal WS1 containing control information for the second switch 23b. Also, in Fig. 19, a dashed arrow pointing from the second power receiving coil 20b to the second power transmitting coil 10b indicates a second wireless signal WS2 containing information about the output power of the second power receiving circuit 21b.

[0112] In this embodiment, as shown in FIG. 20 , each of the multiple power transmitting circuits 11 includes a DC-AC conversion circuit 110 and a first modulation / demodulation circuit 17. The first modulation / demodulation circuit 17 is a circuit for receiving a second wireless signal WS2 containing information about output power and transmitting a first wireless signal WS1 containing control information via the corresponding power transmitting coil 10. More specifically, the first modulation / demodulation circuit 17 has a modulation function for modulating the first wireless signal WS1 and a demodulation function for demodulating the second wireless signal WS2. Each of the multiple power receiving circuits 21 includes a rectifier circuit 211 and a second modulation / demodulation circuit 27. The second modulation / demodulation circuit 27 is a circuit for transmitting a second wireless signal WS2 containing information about output power and receiving a first wireless signal WS1 containing control information via the corresponding power receiving coil 20. More specifically, the second modulation / demodulation circuit 27 has a modulation function for modulating the second wireless signal WS2 and a demodulation function for demodulating the first wireless signal WS1.

[0113] (2) Advantages Like the wireless power feeding system 3 according to the first embodiment, the wireless power feeding system 3C according to the fourth embodiment can increase the DC power obtained at the power receiving terminal 2C and improve the power efficiency.

[0114] Furthermore, the wireless power feeding system 3C according to the fourth embodiment allows each of the multiple power transmitting coils 10 and the multiple power receiving coils 20 to also serve as an antenna for communication.

[0115] Fifth Embodiment A wireless power feeding system 3D according to a fifth embodiment will be described below with reference to Fig. 22. Regarding the wireless power feeding system 3D according to the fifth embodiment, components similar to those of the wireless power feeding system 3 according to the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0116] (1) Configuration As shown in FIG. 22, the wireless power feeding system 3D differs from the wireless power feeding system 3 according to the first embodiment in that it includes a power receiving terminal 2D instead of the power receiving terminal 2 of the wireless power feeding system 3 according to the first embodiment.

[0117] The power receiving terminal 2D differs from the first embodiment in that each of the two switches 23 is a single-pole switch.

[0118] (2) Advantages Like the wireless power feeding system 3 according to the first embodiment, the wireless power feeding system 3D according to the fifth embodiment can increase the DC power obtained at the power receiving terminal 2D and improve the power efficiency.

[0119] Furthermore, the power receiving terminal 2D according to the fifth embodiment can be manufactured at a lower cost than the power receiving terminal 2.

[0120] (Other Modifications) The above-described first to fifth embodiments are merely examples of various embodiments of the present disclosure. The above-described embodiments can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved.

[0121] 23 and 24, the power receiving terminal 2 can also receive power from a power transmitter 1R that has only one power transmitting coil 10. Fig. 23 shows an example in which the power transmitting coil 10 of the power transmitter 1R faces the first power receiving coil 20a of the power receiving terminal 2, and Fig. 24 shows an example in which the power transmitting coil 10 of the power transmitter 1R faces the second power receiving coil 20b of the power receiving terminal 2.

[0122] In the example of Fig. 23, the second controller 22 of the power receiving terminal 2 turns on the first switch 23a and turns off the second switch 23b. In the example of Fig. 24, the second controller 22 of the power receiving terminal 2 turns off the first switch 23a and turns on the second switch 23b.

[0123] (Aspects) The present specification discloses the following aspects.

[0124] A wireless power supply system (3; 3A; 3B; 3C; 3D) according to a first aspect includes a power transmitter (1; 1B) and a power receiving terminal (2; 2A; 2B; 2C; 2D). The power receiving terminal (2; 2A; 2B; 2C; 2D) is supplied with power from the power transmitter (1; 1B; 1C). The power transmitter (1; 1B; 1C) includes a plurality of power transmitting coils (10), a plurality of power transmitting circuits (11), a first controller (12), and a plurality of first measurement circuits (13). The plurality of power transmitting circuits (11) correspond one-to-one to the plurality of power transmitting coils (10). The plurality of power transmitting circuits (11) supply transmission power to a corresponding one of the plurality of power transmitting coils (10). The first controller (12) controls the plurality of power transmitting circuits (11). The multiple first measurement circuits (13) correspond one-to-one to the multiple power transmission circuits (11). The multiple first measurement circuits (13) measure voltages and currents related to input power of corresponding power transmission circuits (11) among the multiple power transmission circuits (11). The power receiving terminal (2; 2A; 2B; 2C; 2D) has multiple power receiving coils (20), multiple power receiving circuits (21), a DC output unit (24), multiple switches (23), a second controller (22), and at least one second measurement circuit (25; 25A). The multiple power receiving coils (20) receive AC power from opposing power transmission coils (10) among the multiple power transmission coils (10). The multiple power receiving circuits (21) correspond one-to-one to the multiple power receiving coils (20). The plurality of power receiving circuits (21) convert AC power received by a corresponding one of the plurality of power receiving coils (20) into DC power. The DC output unit (24) includes a first DC output terminal (241) and a second DC output terminal (242). The first DC output terminal (241) is commonly connected to the high-potential output terminals of the plurality of power receiving circuits (21). The second DC output terminal (242) is commonly connected to the low-potential output terminals of the plurality of power receiving circuits (21). The plurality of switches (23) correspond one-to-one to the plurality of power receiving circuits (21). The plurality of switches (23) are connected between the corresponding one of the plurality of power receiving circuits (21) and the DC output unit (24). The second controller (22) controls the plurality of switches (23). At least one second measurement circuit (25; 25A) measures voltages and currents related to the output power of the plurality of power receiving circuits (21).The first controller (12) calculates power efficiency based on information on input power of the power transmission circuit (11) and information on output power of the power receiving circuit (21), and controls the multiple power transmission circuits (11) based on information on output power and power efficiency of the power receiving circuit (21). The second controller (22) controls the multiple switches (23) based on control information for the multiple switches (23) from the first controller (12).

[0125] According to this aspect, it is possible to increase the DC power obtained at the power receiving terminal (2; 2A; 2B; 2C; 2D) and improve the power efficiency.

[0126] In a wireless power supply system (3; 3A; 3D) according to a second aspect, in the first aspect, the power transmitter (1) further includes a first communication circuit (16). The power receiving terminal (2; 2A; 2D) further includes a second communication circuit (26). The second controller (22) causes the second communication circuit (26) to transmit a second wireless signal (WS2) including output power information to the first communication circuit (16), and acquires control information included in the first wireless signal (WS1) transmitted from the first communication circuit (16) and received by the second communication circuit (26). The first controller (12) acquires the output power information included in the second wireless signal (WS2) received by the first communication circuit (16), and causes the first communication circuit (16) to transmit the first wireless signal (WS1) including the control information to the second communication circuit (26).

[0127] According to this aspect, it is possible to improve the communication performance between the power transmitter (1) and the power receiving terminal (2; 2A; 2D).

[0128] In the wireless power supply system (3; 3A; 3B; 3C; 3D) according to the third aspect, in the first or second aspect, when the total received power based on the information on the output power is equal to or less than a threshold, the first controller (12) stops the operation of some of the multiple power transmission circuits (11) and transmits, as control information to the second controller (22), off control information for turning off switches (23) connected between the DC output unit (24) and the multiple power receiving circuits (21) corresponding to the some of the power transmission circuits (11) among the multiple power receiving circuits (21).

[0129] According to this aspect, when the output power required by the power receiving terminal (2; 2A; 2D) decreases and the total received power becomes equal to or less than the threshold, it is possible to improve the power efficiency.

[0130] In the wireless power supply system (3) according to the fourth aspect, in the third aspect, the first controller (12) determines, based on information on power efficiency, which of the plurality of power transmission circuits (11) to stop and which of the plurality of switches (23) to turn off.

[0131] According to this aspect, it is possible to prevent backflow from occurring between a plurality of power receiving circuits (21).

[0132] In a wireless power supply system (3C) according to a fifth aspect, in the first aspect, each of the plurality of power transmitting circuits (11) includes a first modulation / demodulation circuit (17) for receiving a second wireless signal (WS2) including information on output power and transmitting a first wireless signal (WS1) including control information via a corresponding power transmitting coil (10). Each of the plurality of power receiving circuits (21) includes a second modulation / demodulation circuit (27) for transmitting the second wireless signal (WS2) and receiving the first wireless signal (WS1) via a corresponding power receiving coil (20).

[0133] According to this aspect, each of the plurality of power transmitting coils (10) and the plurality of power receiving coils (20) can be used as an antenna for communication.

[0134] A power receiving terminal (2; 2A; 2B; 2C; 2D) according to a sixth aspect includes a plurality of power receiving coils (20), a plurality of power receiving circuits (21), a DC output unit (24), a plurality of switches (23), a controller (second controller 22), and at least one measurement circuit (second measurement circuit 25; second measurement circuit 25A). The plurality of power receiving circuits (21) correspond one-to-one to the plurality of power receiving coils (20) and convert AC power received by a corresponding power receiving coil (20) among the plurality of power receiving coils (20) into DC power. The DC output unit (24) includes a first DC output terminal (241) to which high-potential-side output terminals of the plurality of power receiving circuits (21) are commonly connected, and a second DC output terminal (242) to which low-potential-side output terminals of the plurality of power receiving circuits (21) are commonly connected. The multiple switches (23) correspond one-to-one to the multiple power receiving circuits (21) and are connected between a corresponding one of the multiple power receiving circuits (21) and the DC output unit (24). A controller (second controller 22) controls the multiple switches (23). At least one measurement circuit (second measurement circuit 25; second measurement circuit 25A) measures voltages and currents related to the output power of the multiple power receiving circuits (21). The controller (second controller 22) controls the multiple switches (23) based on control information for the multiple switches (23).

[0135] According to this aspect, it is possible to increase the DC power obtained at the power receiving terminal (2; 2A; 2B; 2C; 2D) and improve the power efficiency.

[0136] A power transmitter (1; 1B; 1C) according to a seventh aspect includes a plurality of power transmission coils (10), a plurality of power transmission circuits (11), a controller (first controller 12), and a measurement circuit (first measurement circuit 13). The plurality of power transmission circuits (11) correspond one-to-one to the plurality of power transmission coils (10), and supply transmission power to a corresponding power transmission coil (10) among the plurality of power transmission coils (10). The controller (first controller 12) controls the plurality of power transmission circuits (11). The plurality of measurement circuits (first measurement circuit 13) correspond one-to-one to the plurality of power transmission circuits (11), and measure a voltage and a current related to input power of a corresponding power transmission circuit (11) among the plurality of power transmission circuits (11). The controller (first controller 12) calculates power efficiency based on information on input power and information on output power of the power receiving terminals (2; 2A; 2B; 2D), and controls multiple power transmission circuits (11) based on information on output power and information on power efficiency.

[0137] According to this aspect, it is possible to increase the DC power obtained at the power receiving terminal (2; 2A; 2B; 2C; 2D) and improve the power efficiency.

[0138] REFERENCE SIGNS LIST 1, 1B, 1C Power transmitter 10 Power transmitting coil 11 Power transmitting circuit 12 First controller 13 First measuring circuit 16 First communication circuit 17 First modulation / demodulation circuit 2, 2A, 2B, 2C, 2D Power receiving terminal 20 Power receiving coil 21 Power receiving circuit 22 Second controller 23 Switch 24 DC output section 241 First DC output terminal 242 Second DC output terminal 25, 25A Second measuring circuit 26 Second communication circuit 27 Second modulation / demodulation circuit 3, 3A, 3B, 3C, 3D Wireless power feeding system WS1 First wireless signal WS2 Second wireless signal

Claims

1. A power receiving terminal comprising: a power transmitter; and a power receiving terminal to which power is supplied from the power transmitter, wherein the power transmitter comprises: a plurality of power transmitting coils; a plurality of power transmitting circuits each corresponding to the plurality of power transmitting coils and supplying transmitted power to a corresponding one of the plurality of power transmitting coils; a first controller for controlling the plurality of power transmitting circuits; and a plurality of first measurement circuits each corresponding to the plurality of power transmitting circuits and measuring voltages and currents related to input power of a corresponding one of the plurality of power transmitting circuits, wherein the power receiving terminal comprises: a plurality of power receiving coils each receiving AC power from an opposing power transmitting coil of the plurality of power transmitting coils; a plurality of power receiving circuits each corresponding to the plurality of power receiving coils and converting the AC power received by a corresponding one of the plurality of power receiving coils into DC power; a DC output unit including a first DC output terminal to which high potential side output terminals of the plurality of power receiving circuits are commonly connected and a second DC output terminal to which low potential side output terminals of the plurality of power receiving circuits are commonly connected; a plurality of switches each corresponding to one of the plurality of power receiving circuits and connected between a corresponding one of the plurality of power receiving circuits and the DC output unit; a second controller that controls the plurality of switches; and at least one second measurement circuit that measures a voltage and a current related to an output power of the plurality of power receiving circuits, wherein the first controller calculates power efficiency based on information about the input power and information about the output power, and controls the plurality of power transmitting circuits based on information about the output power and information about the power efficiency, and the second controller controls the plurality of switches based on control information about the plurality of switches from the first controller.

2. The wireless power supply system according to claim 1, wherein the power transmitter further has a first communication circuit, the power receiving terminal further has a second communication circuit, the second controller causes a second wireless signal including the information on the output power to be transmitted from the second communication circuit to the first communication circuit, and acquires the control information included in the first wireless signal transmitted from the first communication circuit and received by the second communication circuit, and the first controller acquires the information on the output power included in the second wireless signal received by the first communication circuit, and transmits the first wireless signal including the control information from the first communication circuit to the second communication circuit.

3. The wireless power supply system according to claim 1 or 2, wherein the first controller stops operation of some of the plurality of power transmission circuits when the total received power based on the information on the output power is equal to or less than a threshold, and transmits to the second controller off control information including the control information for turning off switches connected between the DC output unit and power receiving circuits corresponding to some of the plurality of power transmission circuits in the plurality of switches.

4. The wireless power supply system according to claim 3, wherein the first controller determines which of the plurality of power transmission circuits to stop and which of the plurality of switches to turn off based on the information on the power efficiency.

5. The wireless power supply system according to claim 1, wherein each of the plurality of power transmitting circuits includes a first modulation / demodulation circuit for receiving a second wireless signal including information on the input power and transmitting a first wireless signal including the control information via the corresponding power transmitting coil, and each of the plurality of power receiving circuits includes a second modulation / demodulation circuit for transmitting the second wireless signal and receiving the first wireless signal via the corresponding power receiving coil.

6. A power receiving terminal comprising: a plurality of receiving coils; a plurality of receiving circuits each corresponding to the plurality of receiving coils and converting AC power received by a corresponding one of the plurality of receiving coils into DC power; a DC output unit including a first DC output terminal to which the high potential side output terminals of the plurality of receiving circuits are commonly connected and a second DC output terminal to which the low potential side output terminals of the plurality of receiving circuits are commonly connected; a plurality of switches each corresponding to the plurality of receiving circuits and connected between a corresponding one of the plurality of receiving circuits and the DC output unit; a controller for controlling the plurality of switches; and at least one measurement circuit for measuring voltage and current related to the output power of the plurality of receiving circuits, wherein the controller controls the plurality of switches based on control information of the plurality of switches.

7. A power transmitter comprising: a plurality of power transmission coils; a plurality of power transmission circuits each corresponding to the plurality of power transmission coils and supplying transmission power to a corresponding one of the plurality of power transmission coils; a controller for controlling the plurality of power transmission circuits; and a plurality of measurement circuits each corresponding to the plurality of power transmission circuits and measuring voltages and currents related to input power of a corresponding one of the plurality of power transmission circuits, wherein the controller calculates power efficiency based on information about the input power and information about the output power of a power receiving terminal, and controls the plurality of power transmission circuits based on information about the output power and information about the power efficiency.

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