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

Abstract

The present invention increases transmission power and improves power efficiency. Each of a plurality of power transmission circuits (11) outputs AC power to a corresponding power transmission coil (10) among a plurality of power transmission coils (10). A power reception terminal (2) comprises: a plurality of power reception coils (20); a plurality of power reception circuits (21); and a DC output unit (24). Each of the plurality of power reception circuits (21) converts, into DC power, the AC power received by a corresponding power reception coil (20) among the plurality of power reception coils (20). The DC output unit (24) includes a first DC output terminal (241) and a second DC output terminal (242). A controller (12) acquires information on the output voltage of each of the plurality of power reception circuits (21) by means of a wireless signal (W2) from the power reception circuit (21), and controls at least one of the frequency and the power of a power transmission wave of each of the plurality of power transmission circuits (11) so that the output voltages of the plurality of power reception circuits (21) become the same.

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 power received by the power receiving terminal, and the power efficiency may be reduced.

[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 are capable of increasing the power received by the power receiving terminal and improving 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, and a controller. The plurality of power transmitting circuits correspond one-to-one with the plurality of power transmitting coils and supply transmitting power to a corresponding one of the plurality of power transmitting coils. The controller controls the plurality of power transmitting circuits. Each of the plurality of power transmitting circuits outputs AC power to a corresponding one of the plurality of power transmitting coils. The power receiving terminal includes a plurality of power receiving coils, a plurality of power receiving circuits, and a DC output unit. The plurality of power receiving coils receive AC power from opposing power transmitting coils among the plurality of power transmitting coils. The plurality of power receiving circuits correspond one-to-one with the plurality of power receiving coils and convert AC power received by a corresponding one of the plurality of 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 a high-potential side output terminal of each of the plurality of power receiving circuits, and the second DC output terminal is commonly connected to a low-potential side output terminal of each of the plurality of power receiving circuits. The controller acquires information on the output voltage of each of the plurality of power receiving circuits via a wireless signal from each of the plurality of power receiving circuits, and controls at least one of the frequency and power of the transmission radio waves of each of the plurality of power transmitting circuits so that the output voltages of the plurality of power receiving circuits are the same.

[0007] A power receiving terminal according to one aspect of the present disclosure is supplied with power by a power transmitter having a plurality of power transmitting coils. The power receiving terminal includes a plurality of power receiving coils, a plurality of power receiving circuits, and a DC output unit. 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 one of the plurality of 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 a high-potential output terminal of each of the plurality of power receiving circuits. The second DC output terminal is commonly connected to a low-potential output terminal of each of the plurality of power receiving circuits. The power receiving terminal transmits information about the output voltage of each of the plurality of power receiving circuits to the power transmitter via a wireless signal from each of the plurality of power receiving circuits.

[0008] A power transmitter according to one aspect of the present disclosure wirelessly transmits power to a power receiving terminal. The power transmitter includes a plurality of power transmitting coils, a plurality of power transmitting circuits, and a controller. The plurality of power transmitting circuits correspond one-to-one with 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. Each of the plurality of power transmitting circuits outputs AC power to a corresponding one of the plurality of power transmitting coils. The power receiving terminal includes a plurality of power receiving coils, a plurality of power receiving circuits, and a DC output unit. The plurality of power receiving coils receive AC power from an opposing one of the plurality of power transmitting coils. The plurality of power receiving circuits correspond one-to-one with the plurality of power receiving coils and convert the AC power received by a corresponding one of the plurality of 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 a high-potential side output terminal of each of the plurality of power receiving circuits, and the second DC output terminal is commonly connected to a low-potential side output terminal of each of the plurality of power receiving circuits. The controller acquires information on the output voltage of each of the plurality of power receiving circuits via a wireless signal from each of the plurality of power receiving circuits, and controls at least one of the frequency and power of the transmission radio waves of each of the plurality of power transmitting circuits so that the output voltages of the plurality of power receiving circuits are the same.

[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 circuit diagram of a power receiving circuit included in a power receiving terminal in the wireless power feeding system. FIG. 4 is a schematic exploded perspective view of a power transmitter in the wireless power feeding system. FIG. 5 is a schematic plan view of a housing of a power transmitter and a mobile system in the wireless power feeding system. FIG. 6 is a flowchart illustrating the operation of a power transmitter according to the first embodiment. FIG. 7 is a configuration diagram of a wireless power feeding system according to a second embodiment. FIG. 8 is a configuration diagram of a main part of a power transmitter in the wireless power feeding system. FIG. 9 is a configuration diagram of a main part of a power receiving terminal in the wireless power feeding system. FIG. 10 is a configuration diagram of a main part of a power transmitter in a wireless power feeding system according to a third embodiment. FIG. 11 is a configuration diagram of a main part of a power receiving terminal in the wireless power feeding system. FIG. 12 is a configuration diagram of a wireless power feeding system according to a fourth embodiment. Fig. 13 is a configuration diagram of a main part of a power transmitter in the wireless power feeding system of the same. Fig. 14 is a configuration diagram of a main part of a power receiving terminal in the same wireless power feeding system. Fig. 15 is a configuration diagram of a main part of a power transmitter in the wireless power feeding system according to embodiment 5. Fig. 16 is a configuration diagram of a main part of a power receiving terminal in the same wireless power feeding system. Fig. 17 is a configuration diagram of a wireless power feeding system according to embodiment 6. Fig. 18 is a configuration diagram of a main part of a power transmitter in the wireless power feeding system of the same. Fig. 19 is a configuration diagram of a main part of a power receiving terminal in the wireless power feeding system of the same. Fig. 20 is a configuration diagram of a main part of a power transmitter in the wireless power feeding system according to embodiment 7. 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 8. Fig. 23 is a configuration diagram of a main part of a power receiving terminal in the wireless power feeding system of the same. Fig. 24 is a configuration diagram of a main part of a power receiving terminal in a wireless power feeding system according to a modification of embodiment 8. Fig. 25 is a configuration diagram of a wireless power feeding system according to embodiment 9. Fig. 26 is a diagram illustrating the operation of a wireless power feeding system according to embodiment 10. Fig. 27 is a diagram illustrating the operation of the wireless power feeding system according to the same. Fig. 28 is a characteristic diagram of power efficiency in the wireless power feeding system according to the same. Fig. 29 is a configuration diagram of the wireless power feeding system according to the same. Fig. 30 is a configuration diagram of a wireless power feeding system according to a modification of embodiment 10.Fig. 31 is a configuration diagram of a wireless power feeding system according to embodiment 11. Fig. 32 is a configuration diagram of a wireless power feeding system including the power transmitter according to embodiment 1 and a power receiving terminal having only one power receiving coil.

[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 6. 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, and a controller 12. The plurality of power transmitting circuits 11 correspond one-to-one to the plurality of power transmitting coils 10 and supply transmission power to a corresponding one of the plurality of power transmitting coils 10. The controller 12 controls the plurality of power transmitting circuits 11. Each of the plurality of power transmitting circuits 11 outputs AC power to a corresponding one of the plurality of power transmitting coils 10. 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, and a DC output unit 24. The multiple power receiving coils 20 receive AC power from opposing power transmitting coils 10 among the multiple power transmitting coils 10. The multiple power receiving circuits 21 correspond one-to-one to the multiple power receiving coils 20 and convert the AC power received by a corresponding one of the multiple 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 multiple power receiving circuits 21. The second DC output terminal 242 is commonly connected to the low-potential output terminals of the multiple power receiving circuits 21. The controller 12 acquires information about the output voltage of each of the multiple power receiving circuits 21 via a wireless signal W2 from each of the multiple power receiving circuits 21 and controls at least one of the frequency and power of the power transmission radio waves of each of the multiple power transmitting circuits 11 so that the output voltages of the multiple power receiving circuits 21 are the same.

[0013] According to the above configuration, it is possible to increase the power received by the power receiving terminal 2 and improve the power efficiency.

[0014] The DC output unit 24 is connected to, for example, a battery (e.g., a lithium ion battery) for storing electrical energy, but is not limited to a battery and may also be connected to, for example, a load that operates using electrical energy.

[0015] In the wireless power feeding system 3 , the power transmitter 1 further includes a power supply circuit 19 .

[0016] 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.

[0017] (2) Details Each component of the wireless power supply system 3 will be described in more detail below.

[0018] (2.1) Power Transmitter As shown in FIG. 1 , the power transmitter 1 includes two power transmission coils 10 , two power transmission circuits 11 , a power supply circuit 19 , and a controller 12 .

[0019] 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.

[0020] 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.

[0021] Each of the two power transmission circuits 11 includes a DC-AC conversion circuit 110 (see FIG. 2) 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. The DC-AC conversion circuit 110 can change the frequency of the AC voltage output from the DC-AC conversion circuit 110 and the output power of the DC-AC conversion circuit 110.

[0022] The capacitor C11 is connected between the output terminals of the power supply circuit 19 (see FIG. 1 ). 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.

[0023] 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.

[0024] 1 , the power supply circuit 19 supplies a power supply voltage between a pair of input / output terminals of the two power transmission circuits 11. 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 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.

[0025] The controller 12 controls the two power transmitting circuits 11. The controller 12 has a first communication circuit (not shown) for receiving a wireless signal W2. The controller 12 acquires information about the output voltage of each of the multiple power receiving circuits 21 via the wireless signal W2 from each of the multiple (two in the example of FIG. 1 ) power receiving circuits 21, and controls at least one of the frequency and power of the power transmission radio waves of each of the multiple power transmitting circuits 11 so that the output voltages of the multiple power receiving circuits 21 are the same. The phrase "the output voltages of the multiple power receiving circuits 21 are the same" does not necessarily mean that the output voltages of the multiple power receiving circuits 21 are strictly the same, but may mean that the output voltage of one power receiving circuit is 95% to 105% of the output voltages of the remaining power receiving circuits. In this embodiment, the multiple power receiving circuits 21 include a first power receiving circuit 21a and a second power receiving circuit 21b, and the wireless signal W2 acquired by the controller 12 from each of the multiple power receiving circuits 21 includes a wireless signal W2a from the first power receiving circuit 21a and a wireless signal W2b from the second power receiving circuit 21b. The controller 12 controls the frequency of the transmitted radio waves, for example, by instructing the control circuit 115 in the DC-AC conversion circuit 110 (see FIG. 2) to change the frequency of the output voltage of the DC-AC conversion circuit 110. The controller 12 also controls the power of the transmitted radio waves, for example, by instructing the control circuit 115 in the DC-AC conversion circuit 110 to change the output power of the DC-AC conversion circuit 110.

[0026] In the present embodiment, the controller 12 is configured to be able to switch between a first power transmission mode and a second power transmission mode as the operating mode of the power transmitter 1. 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. The term "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 10 a and a first power receiving coil 20 a (hereinafter also referred to as a first pair) and a coil pair of a second power transmitting coil 10 b and a second power receiving coil 20 b (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. 32 ) using one coil pair. The power receiving terminal 2R differs from the power receiving terminal 2 in that the power receiving terminal 2R has one power receiving coil 20. The power transmitter 1 can transmit a larger amount of power in the first power transmission mode than in the second power transmission mode.

[0027] The controller 12 includes a computer system. The computer system is primarily composed of a processor and memory as hardware. The functions of the controller 12 in the present disclosure are realized by the processor executing a program stored in the computer system's memory. The program may be pre-recorded in the computer system's memory, provided via a telecommunications line, or provided in a non-transitory recording medium such as a memory card, optical disk, or hard disk drive that is readable by the computer system. 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 that allow the reconfiguration of internal connections or internal circuit partitions of 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.

[0028] As shown in Fig. 4 , the power transmitter 1 further includes a housing 40, a movement system 50, and a position detection device 60. The housing 40 houses two power transmitting coils 10, two power transmitting circuits 11, a controller 12, a power supply circuit 19, and the movement system 50. Note that the two power transmitting circuits 11, the controller 12, and the power supply circuit 19 are not shown in Figs. 4 and 5 .

[0029] The housing 40 is in the shape of a rectangular box with an opening on one side.

[0030] 4 and 5 , 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.

[0031] 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.

[0032] 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.

[0033] 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 .

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] The movement system 50 is controlled by, for example, the 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 controller 12.

[0044] 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.

[0045] 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. 4 , 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. 4 ) and a plurality of second search coils 62 (four in the example of FIG. 4 ). 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.

[0046] 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.

[0047] 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.

[0048] 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 (orthogonal) 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 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).

[0049] The controller 12 supplies pulse signals to the plurality of first search coils 61 and the plurality of second search coils 62 .

[0050] 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 controller 12. The 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 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.

[0051] 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 controller 12. The 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 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.

[0052] 32, 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.

[0053] (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 , and a DC output unit 24 .

[0054] 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.

[0055] 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.

[0056] 3, each of the plurality of power receiving circuits 21 includes a rectifier circuit 211. In the example of FIG. 3, the rectifier circuit 211 includes four switching elements Q21, Q22, Q23, and Q24, a capacitor C21, and a control circuit 215.

[0057] 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.

[0058] 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. 3, 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.

[0059] 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.

[0060] Each of the two power receiving circuits 21 further includes a voltage measurement circuit 22 that measures the output voltage of the power receiving circuit 21 (the output voltage of the rectifier circuit 211), and a second communication circuit 26. The voltage measurement circuit 22 includes, for example, a resistive voltage divider circuit. The second communication circuit 26 has an antenna. The second communication circuit 26 also has an RFIC (Radio Frequency Integrated Circuit) connected to the antenna. The second communication circuit 26 can wirelessly communicate with the first communication circuit of the controller 12 and transmits a wireless signal W2 to the first communication circuit of the controller 12.

[0061] 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.

[0062] (3) Operation of Wireless Power Supply System An example of the operation of the power transmitter 1 will be described below with reference to FIG.

[0063] When the 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 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. 32 (for example, the power receiving terminal 2R on the left in FIG. 32) is placed on the power transmitter 1.

[0064] After step S3, the 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, and starts power transmission from the power transmitting coil 10 to the power receiving coil 20 (step S5). After step S5, if another power receiving coil 20 is detected (step S6: Yes), the controller 12 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 operation of the power transmitting circuit 11 is terminated. 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.

[0065] Furthermore, if the number of power receiving coils 20 detected in step S1 is multiple (for example, two) (step S2: No), the 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 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 controller 12 proceeds to step S3.

[0066] After step S11, the controller 12 identifies the positions of all (e.g., two) receiving coils 20 (step S12). Then, the controller 12 moves the first power transmitting coil 10a using the moving system 50 so that it faces the first power receiving coil 20a, and starts power transmission from the first power transmitting coil 10a to the first power receiving coil 20a (step S13). Then, the controller 12 moves the second power transmitting coil 10b using the moving system 50 so that it faces the second power receiving coil 20b, and starts power transmission from the second power transmitting coil 10b to the second power receiving coil 20b (step S14). After step S14, when power transmission to all (e.g., two) receiving coils 20 is completed (step S9), the controller 12 ends the operation of the power transmitting circuit 11.

[0067] (4) Advantages In the wireless power feeding system 3 according to the first embodiment, each of the multiple power transmitting circuits 11 outputs AC power to a corresponding one of the multiple power transmitting coils 10. The power receiving terminal 2 includes multiple power receiving coils 20, multiple power receiving circuits 21, and a DC output unit 24. The DC output unit 24 includes a first DC output terminal 241 and a second DC output terminal 242. The controller 12 acquires information about the output voltage of each of the multiple power receiving circuits 21 via a wireless signal W2 from each of the multiple power receiving circuits 21, and controls at least one of the frequency and power of the power transmission radio waves of each of the multiple power transmitting circuits 11 so that the output voltages of the multiple power receiving circuits 21 are the same.

[0068] The above configuration enables the power receiving terminal 2 to receive a larger amount of power and to improve power efficiency. More specifically, in the wireless power feeding system 3 according to the first embodiment, the power transmitter 1 includes two power transmitting coils 10, the power receiving terminal 2 includes two power receiving coils 20, and the power receiving terminal 2 can combine the received powers. This enables the power receiving terminal 2 to receive a larger amount of power. In a wireless power feeding system, the optimal conditions for the power transmitting radio waves differ for each pair of a power transmitting coil and a power receiving coil, and the output voltage of the power receiving circuit connected to the power receiving coil may differ. However, in the wireless power feeding system 3 according to the first embodiment, the power transmitter 1 includes multiple power transmitting circuits 11, and the controller 12 controls at least one of the frequency and power of the power transmitting radio waves of each of the multiple power transmitting circuits 11 so that the output voltages of the multiple power receiving circuits 21 are the same. This makes it possible to prevent current from flowing between the power receiving circuits 21 due to differences in output voltage between the multiple power receiving circuits 21, thereby improving power efficiency.

[0069] In the wireless power feeding system 3 according to the first embodiment, the power receiving terminal 2 transmits a wireless signal W2 from each of the plurality of power receiving circuits 21 to the controller 12 .

[0070] According to the above configuration, it is not necessary for each of the plurality of power transmission circuits 11 to receive the wireless signal W2, and therefore it is possible to reduce the size and weight of the power transmitter 1.

[0071] Furthermore, the power receiving terminal 2 according to the first embodiment is supplied with power by a power transmitter 1 having a plurality of power transmitting coils 10. The power receiving terminal 2 includes a plurality of power receiving coils 20, a plurality of power receiving circuits 21, and a DC output unit 24. 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 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 power receiving terminal 2 transmits information about the output voltage of each of the plurality of power receiving circuits 21 to the power transmitter 1 via a wireless signal W2 from each of the plurality of power receiving circuits 21.

[0072] According to the above configuration, it is possible to increase the power received by the power receiving terminal 2 and improve the power efficiency.

[0073] A power transmitter 1 according to a first embodiment wirelessly transmits power to a power receiving terminal 2. The power transmitter 1 includes a plurality of power transmitting coils 10, a plurality of power transmitting circuits 11, and a controller 12. The plurality of power transmitting circuits 11 correspond one-to-one to the plurality of power transmitting coils 10 and supply transmission power to a corresponding one of the plurality of power transmitting coils 10. The controller 12 controls the plurality of power transmitting circuits 11. Each of the plurality of power transmitting circuits 11 outputs AC power to a corresponding one of the plurality of power transmitting coils 10. The power receiving terminal 2 includes a plurality of power receiving coils 20, a plurality of power receiving circuits 21, and a DC output unit 24. 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 and 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 multiple power receiving circuits 21. The second DC output terminal 242 is commonly connected to the low-potential output terminals of the multiple power receiving circuits 21. The controller 12 acquires information about the output voltage of each of the multiple power receiving circuits 21 via a wireless signal W2 from each of the multiple power receiving circuits 21, and controls at least one of the frequency and power of the power transmission radio waves of each of the multiple power transmitting circuits 11 so that the output voltages of the multiple power receiving circuits 21 are the same.

[0074] According to the above configuration, it is possible to increase the power received by the power receiving terminal 2 and improve the power efficiency.

[0075] (Embodiment 2) A wireless power feeding system 3A according to embodiment 2 will be described below with reference to Fig. 7 to Fig. 9. 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.

[0076] (1) Configuration As shown in Fig. 7 , 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 transmitter 1A and a power receiving terminal 2A instead of the power transmitter 1 and the power receiving terminal 2 according to the first embodiment. Regarding the power transmitter 1A, the same components as those of the power transmitter 1 are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate. Regarding the power receiving terminal 2A, the same components as those of the power receiving terminal 2 are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0077] The wireless power supply system 3A is configured to transmit a wireless signal W2 from each of a plurality of (two in the example of Figure 7) power receiving circuits 21 to a corresponding one of a plurality of (two in the example of Figure 7) power transmitting circuits 11.

[0078] Each of the multiple power transmitting circuits 11 further includes a first communication circuit 16 (see FIG. 8 ). Each of the multiple power receiving circuits 21 further includes a second communication circuit 26 (see FIG. 9 ). Each first communication circuit 16 has a first antenna. Each second communication circuit 26 has a second antenna. The power receiving terminal 2A transmits a wireless signal W2 from the second communication circuit 26 of each of the multiple power receiving circuits 21 to the first communication circuit 16 of each of the multiple power transmitting circuits 11. The controller 12 acquires information about the output voltage of each of the multiple power receiving circuits 21 from the multiple first communication circuits 16. The controller 12 controls the power of the transmission radio waves by controlling the DC-AC conversion circuit 110 (see FIG. 8 ) of the power transmitting circuit 11 based on the information about the output voltage of each of the multiple power receiving circuits 21.

[0079] Each of the power receiving circuits 21 has a voltage measurement circuit 22 (see FIG. 9 ) that measures the output voltage of the power receiving circuit 21. The voltage measurement circuit 22 is, for example, a resistive voltage divider circuit. The second communication circuit 26 transmits a wireless signal W2 to the first communication circuit 16, the wireless signal W2 including data on the voltage value measured by the voltage measurement circuit 22 as the output voltage of the power receiving circuit 21.

[0080] In the wireless power feeding system 3A according to the second embodiment, the controller 12 starts power transmission after determining the transmission power at which the output voltage of the power receiving circuit 21 becomes a predetermined value at a predetermined frequency of a power transmission radio wave (hereinafter also referred to as a power transmission frequency) for each power receiving coil 20. More specifically, the controller 12 executes a first step of determining the transmission power and a second step of continuing power transmission after the first step.

[0081] In the first step, the controller 12 fixes the frequency of the transmission radio waves to a predetermined transmission frequency fi (i = 1, 2, ...), changes the transmission power from each transmission coil 10, and transmits it (test transmission), thereby determining the transmission power Pi (i = 1, 2, ...) at which the output voltage of the receiving circuit 21 becomes a predetermined DC voltage.

[0082] In the second step, the controller 12 starts power transmission from each power transmitting coil 10 with the frequency of the power transmission radio wave set to fi and the transmission power set to Pi.

[0083] When the controller 12 determines that the frequency of the power transmission radio wave is f1 and the power transmission amount is P1, the controller 12 starts power transmission from the first power transmission coil 10a. When the controller 12 determines that the frequency of the power transmission radio wave is f2 and the power transmission amount is P2, the controller 12 starts power transmission from the second power transmission coil 10b.

[0084] The controller 12 may set all of the frequencies fi (i = 1, 2, ...) of the power transmission radio waves from the power transmitting coils 10 to the same frequency (a preset frequency). In this way, for example, by setting the frequency of the power transmission radio waves to a frequency at which the power transmission circuit 11 has high power efficiency, it is possible to reduce power loss in the power transmitter 1 and reduce heat generation.

[0085] (2) Advantages The wireless power feeding system 3A according to the second embodiment makes it possible to increase the received power and improve the power efficiency at the power receiving terminal 2A.

[0086] Furthermore, in the wireless power feeding system 3A according to the second embodiment, each of the plurality of power receiving circuits 21 of the power receiving terminal 2A can communicate with a corresponding one of the plurality of power transmitting circuits 11 .

[0087] Third Embodiment The basic configuration of a wireless power feeding system 3A according to a third embodiment is the same as the configuration of the wireless power feeding system 3A according to the second embodiment (see FIG. 7), and therefore will not be illustrated or described again.

[0088] (1) Configuration In the third embodiment, as shown in Fig. 10 , each of the multiple power transmitting circuits 11 includes a DC-AC conversion circuit 110, a voltage measurement circuit 13 (hereinafter also referred to as a first voltage measurement circuit 13), a current measurement circuit 14 (hereinafter also referred to as a first current measurement circuit 14), and a first communication circuit 16. The voltage measurement circuit 13 measures the input voltage of the power transmitting circuit 11. The first current measurement circuit 14 measures the input current of the power transmitting circuit 11.

[0089] The first voltage measurement circuit 13 includes, for example, a first resistor voltage divider circuit. The first current measurement circuit 14 includes, for example, a first current detection resistor. The first communication circuit 16 has a first antenna.

[0090] As shown in FIG. 11, each of the multiple power receiving circuits 21 includes a rectifier circuit 211, a voltage measurement circuit 22 (hereinafter also referred to as the second voltage measurement circuit 22), a current measurement circuit 23 (hereinafter also referred to as the second current measurement circuit 23), and a second communication circuit 26.

[0091] The voltage measuring circuit 22 measures the output voltage of the power receiving circuit 21. The current measuring circuit 23 measures the output current of the power receiving circuit 21.

[0092] The second voltage measurement circuit 22 includes, for example, a second resistive voltage divider circuit. The second current measurement circuit 23 includes, for example, a second current detection resistor. The second communication circuit 26 has a second antenna.

[0093] Each of the multiple receiving circuits 21 transmits a wireless signal including data on the measured voltage value of the second voltage measuring circuit 22 and data on the measured current value of the second current measuring circuit 23 from the second communication circuit 26 to the first communication circuit 16 of the corresponding one of the multiple transmitting circuits 11.

[0094] The controller 12 calculates input power using measured voltage value data acquired from the first voltage measurement circuit 13 and measured current value data acquired from the first current measurement circuit 14. The controller 12 calculates output power using measured voltage value data and measured current value data transmitted from the second communication circuit 26 to the first communication circuit 16. The controller 12 calculates power efficiency using the input power and output power. More specifically, the controller 12 calculates power efficiency using the formula: power efficiency = (output power / input power) × 100. The controller 12 controls the frequency of the power transmission radio waves so as to maximize power efficiency.

[0095] In the wireless power feeding system 3A according to the third embodiment, the controller 12 determines the frequency at which the power efficiency is maximized for each power receiving coil 20, and starts power transmission after determining the power at which the output voltage of the power receiving circuit 21 becomes a predetermined value. More specifically, the controller 12 executes a first step of determining the frequency of the power transmission radio wave (hereinafter also referred to as the power transmission frequency), a second step of determining the power to be transmitted after the first step, and a third step of continuing the power transmission after the second step.

[0096] In the first step, the controller 12 fixes the power of the power transmission radio wave to a predetermined value, changes the power transmission frequency from each power transmission coil 10, calculates the power efficiency, and determines the frequency f at which the power efficiency is maximized for each coil pair. ｉ (i=1, 2, ...).

[0097] In the second step, the controller 12 sets the power transmission frequency of each power transmission coil 10 to the frequency f ｉ The power transmission from each power transmission coil 10 is changed and transmitted (test power transmission), and the power transmission power P ｉ (i=1, 2, ...).

[0098] In the third step, the controller 12 sets the frequency of the power transmission radio wave to f ｉ , the transmitted power is P ｉ The controller 12 sets the frequency of the power transmission radio wave to f １ , the transmitted power is P １When it is determined that the frequency of the power transmission wave is f ２ , the transmitted power is P ２ If it is determined that the second power transmission coil 10b is the first power transmission coil, the second power transmission coil 10b starts power transmission.

[0099] (2) Advantages Like the wireless power feeding system 3A according to the second embodiment, the wireless power feeding system 3A according to the third embodiment can increase the received power and improve the power efficiency at the power receiving terminal 2A.

[0100] In the wireless power feeding system 3A according to the third embodiment, the controller 12 controls the frequency of the power transmission radio waves so as to maximize the power efficiency. As a result, the wireless power feeding system 3A according to the third embodiment can maximize the power efficiency, thereby reducing the power transmission and the power consumption.

[0101] (Fourth embodiment) A wireless power feeding system 3B according to a fourth embodiment will be described below with reference to Fig. 12 to Fig. 14. Regarding the wireless power feeding system 3B according to the fourth embodiment, the same components as those in the wireless power feeding system 3A according to the second embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0102] (1) Configuration As shown in Fig. 12 , the wireless power feeding system 3B differs from the wireless power feeding system 3A according to the second embodiment in that it includes a power transmitter 1B and a power receiving terminal 2B instead of the power transmitter 1A and the power receiving terminal 2A according to the second embodiment. Regarding the power transmitter 1B, components similar to those of the power transmitter 1A are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate. Regarding the power receiving terminal 2B, components similar to those of the power receiving terminal 2A are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0103] 12 , the wireless power feeding system 3B 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. In Fig. 12 , the dashed arrow pointing from the first power receiving coil 20a to the first power transmitting coil 10a indicates a wireless signal W2a containing information about the output voltage of the first power receiving circuit 21a. In Fig. 12 , the dashed arrow pointing from the second power receiving coil 20b to the second power transmitting coil 10b indicates a wireless signal W2b containing information about the output voltage of the second power receiving circuit 21b.

[0104] 13 , each of the plurality of power transmitting circuits 11 includes a demodulation circuit 17. The demodulation circuit 17 is a circuit for receiving the wireless signal W2 via the corresponding power transmitting coil 10. More specifically, the demodulation circuit 17 has a demodulation function for demodulating the wireless signal W2.

[0105] 14, each of the plurality of power receiving circuits 21 includes a modulation circuit 27. The modulation circuit 27 is a circuit for transmitting a wireless signal W2 via the corresponding power receiving coil 20. More specifically, the modulation circuit 27 has a modulation function for modulating the wireless signal W2.

[0106] (2) Advantages Like the wireless power feeding system 3A according to the second embodiment, the wireless power feeding system 3B according to the fourth embodiment can increase the received power and improve the power efficiency at the power receiving terminal 2B.

[0107] Furthermore, the wireless power feeding system 3B 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.

[0108] Fifth Embodiment The basic configuration of a wireless power feeding system 3B according to a fifth embodiment is the same as the configuration of the wireless power feeding system 3B according to the fourth embodiment (see FIG. 12), and therefore will not be illustrated or described again.

[0109] (1) Configuration In the fifth embodiment, as shown in FIG. 15 , each of the multiple power transmitting circuits 11 includes a DC-AC conversion circuit 110, a voltage measurement circuit 13 (hereinafter also referred to as a first voltage measurement circuit 13), a current measurement circuit 14 (hereinafter also referred to as a first current measurement circuit 14), and a demodulation circuit 17. The voltage measurement circuit 13 measures the input voltage of the power transmitting circuit 11. The first current measurement circuit 14 measures the input current of the power transmitting circuit 11.

[0110] The first voltage measurement circuit 13 includes, for example, a first resistor voltage divider circuit, and the first current measurement circuit 14 includes, for example, a first current detection resistor.

[0111] As shown in FIG. 16, each of the multiple power receiving circuits 21 includes a rectifier circuit 211, a voltage measurement circuit 22 (hereinafter also referred to as the second voltage measurement circuit 22), a current measurement circuit 23 (hereinafter also referred to as the second current measurement circuit 23), and a modulation circuit 27.

[0112] The voltage measurement circuit 22 measures the output voltage of the power receiving circuit 21. The current measurement circuit 23 measures the output current of the power receiving circuit 21.

[0113] The second voltage measurement circuit 22 includes, for example, a second resistive voltage divider circuit, and the second current measurement circuit 23 includes, for example, a second current detection resistor.

[0114] Each of the multiple receiving circuits 21 transmits a wireless signal W2 including data on the measured voltage value of the second voltage measuring circuit 22 and data on the measured current value of the second current measuring circuit 23 from the modulation circuit 27 to the demodulation circuit 17 of a corresponding one of the multiple transmitting circuits 11.

[0115] The controller 12 calculates the input power to the power transmitting circuit 11 using the measured voltage value data acquired from the first voltage measuring circuit 13 and the measured current value data acquired from the first current measuring circuit 14. The controller 12 calculates the output power of the power receiving circuit 21 using the measured voltage value data and measured current value data transmitted from the modulation circuit 27 to the demodulation circuit 17. The controller 12 calculates the power efficiency using the input power and the output power. More specifically, the controller 12 calculates the power efficiency using the formula: power efficiency = (output power / input power) × 100. The controller 12 controls the frequency of the power transmission radio waves so as to maximize the power efficiency.

[0116] (2) Advantages Like the wireless power feeding system 3B according to the fourth embodiment, the wireless power feeding system 3B according to the fifth embodiment can increase the received power and improve the power efficiency at the power receiving terminal 2B.

[0117] Furthermore, in the wireless power feeding system 3B according to the fifth embodiment, the controller 12 controls the frequency of the power transmission radio waves to maximize the power efficiency, as in the wireless power feeding system 3A according to the third embodiment. As a result, the wireless power feeding system 3B according to the fifth embodiment can maximize the power efficiency, thereby reducing the power transmission and the power consumption.

[0118] Sixth Embodiment A wireless power feeding system 3C according to a sixth embodiment will be described below with reference to Fig. 17 to Fig. 19. Regarding the wireless power feeding system 3C according to the sixth 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.

[0119] (1) Configuration As shown in FIG. 17 , the wireless power supply system 3C differs from the wireless power supply system 3 according to the first embodiment in that the wireless power supply 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 according to the first embodiment.

[0120] 17 and 18 , the power transmitter 1C includes a plurality of (two in the example of FIG. 17 ) power transmission coils 10, a plurality of (two in the example of FIG. 17 ) power transmission circuits 11, a controller 12, a power supply circuit 19, and a first communication circuit 16. The first communication circuit 16 includes a first antenna.

[0121] 17 and 19, the power receiving terminal 2C has a plurality of (two in the example of FIG. 17) power receiving coils 20, a plurality of (two in the example of FIG. 17) power receiving circuits 21, and a second communication circuit 26. The second communication circuit 26 has a second antenna.

[0122] In the power receiving terminal 2C of this embodiment, the second communication circuit 26 acquires the measured value of the output voltage of the power receiving circuit 21 from the voltage measurement circuit 22 of each of the multiple power receiving circuits 21, and transmits a wireless signal W2 containing information on the output voltage of each power receiving circuit 21 to the first communication circuit 16.

[0123] In the power transmitter 1C, the controller 12 acquires information on the output voltage of each power receiving circuit 21 from the first communication circuit 16 and controls each power transmitting circuit 11 .

[0124] (2) Advantages Like the wireless power feeding system 3 according to the first embodiment, the wireless power feeding system 3C according to the sixth embodiment can increase the received power and improve the power efficiency at the power receiving terminal 2C.

[0125] Furthermore, in the wireless power supply system 3C according to the sixth embodiment, it is sufficient to have one first communication circuit 16 and one second communication circuit 26, so it is possible to reduce the size of each of the power transmitter 1C and the power receiving terminal 2C, and also to reduce costs.

[0126] Seventh Embodiment The basic configuration of a wireless power feeding system 3C according to a seventh embodiment is the same as the configuration of the wireless power feeding system 3C according to the sixth embodiment (see FIG. 17), and therefore will not be illustrated or described again.

[0127] (1) Configuration In the seventh embodiment, each of the multiple power transmitting circuits 11 includes a DC-AC conversion circuit 110, a voltage measurement circuit 13 (hereinafter also referred to as a first voltage measurement circuit 13), and a current measurement circuit 14 (hereinafter also referred to as a first current measurement circuit 14), as shown in Fig. 20. The voltage measurement circuit 13 measures the input voltage of the power transmitting circuit 11. The first current measurement circuit 14 measures the input current of the power transmitting circuit 11.

[0128] The first voltage measurement circuit 13 includes, for example, a first resistor voltage divider circuit, and the first current measurement circuit 14 includes, for example, a first current detection resistor.

[0129] As shown in FIG. 21, each of the multiple power receiving circuits 21 includes a rectifier circuit 211, a voltage measurement circuit 22 (hereinafter also referred to as the second voltage measurement circuit 22), and a current measurement circuit 23 (hereinafter also referred to as the second current measurement circuit 23).

[0130] The voltage measurement circuit 22 measures the output voltage of the power receiving circuit 21. The current measurement circuit 23 measures the output current of the power receiving circuit 21.

[0131] The second voltage measurement circuit 22 includes, for example, a second resistive voltage divider circuit, and the second current measurement circuit 23 includes, for example, a second current detection resistor.

[0132] The power receiving terminal 2C transmits a wireless signal W2 including data on the measured voltage value of the second voltage measuring circuit 22 and data on the measured current value of the second current measuring circuit 23 from the second communication circuit 26 to the first communication circuit 16.

[0133] The controller 12 calculates input power using measured voltage value data acquired from the first voltage measurement circuit 13 and measured current value data acquired from the first current measurement circuit 14. The controller 12 calculates output power using measured voltage value data and measured current value data transmitted from the second communication circuit 26 to the first communication circuit 16. The controller 12 calculates power efficiency using the input power and output power. More specifically, the controller 12 calculates power efficiency using the formula: power efficiency = (output power / input power) × 100. The controller 12 controls the frequency of the power transmission radio waves so as to maximize power efficiency.

[0134] (2) Advantages Like the wireless power feeding system 3C according to the sixth embodiment, the wireless power feeding system 3C according to the seventh embodiment makes it possible to increase the received power and improve the power efficiency at the power receiving terminal 2C.

[0135] Furthermore, in the wireless power feeding system 3C according to the seventh embodiment, the controller 12 controls the frequency of the power transmission radio waves to maximize the power efficiency, similarly to the wireless power feeding system 3A according to the third embodiment. As a result, the wireless power feeding system 3C according to the seventh embodiment can maximize the power efficiency, thereby reducing the power transmission and the power consumption.

[0136] Eighth Embodiment A wireless power feeding system 3D according to an eighth embodiment will be described below with reference to Fig. 22 and Fig. 23. Regarding the wireless power feeding system 3D according to the eighth embodiment, the same components as those in the wireless power feeding system 3 according to the first embodiment (see Fig. 1) are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0137] (1) Configuration As shown in FIG. 22, a wireless power feeding system 3D differs from the wireless power feeding system 3 according to the first embodiment in that a power receiving terminal 2D is provided instead of the power receiving terminal 2 according to the first embodiment.

[0138] The power receiving terminal 2D differs from the power receiving terminal 2 in that it further includes a plurality of (two in FIG. 22) diode circuits 25 in one-to-one correspondence with a plurality of (two in FIG. 22) power receiving circuits 21.

[0139] 23 , each of the plurality of diode circuits 25 includes a first diode D25 having an anode connected to the high-potential output terminal of the power receiving circuit 21, and a second diode D26 having a cathode connected to the low-potential output terminal of the power receiving circuit 21. The cathode of the first diode D25 is connected to the first DC output terminal 241 (see FIG. 22 ). The anode of the second diode D26 is connected to the second DC output terminal 242 (see FIG. 22 ).

[0140] (2) Advantages Like the wireless power feeding system 3 according to the first embodiment, the wireless power feeding system 3D according to the eighth embodiment can increase the received power and improve the power efficiency at the power receiving terminal 2D.

[0141] Furthermore, since the wireless power supply system 3D according to the eighth embodiment includes a plurality of diode circuits 25, it is possible to prevent backflow between the plurality of power receiving circuits 21 even when the controllability of the plurality of power transmitting circuits 11 by the controller 12 is reduced.

[0142] (3) Modification of the Eighth Embodiment Each of the plurality of diode circuits 25 is not limited to the example of FIG. 23, and may be configured to include only a first diode D25, as shown in FIG. 24, for example.

[0143] Ninth Embodiment A wireless power feeding system 3E according to a ninth embodiment will be described below with reference to Fig. 25. In the wireless power feeding system 3E according to the ninth embodiment, the same components as those in the wireless power feeding system 3 according to the first embodiment (see Fig. 1) are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0144] (1) Configuration As shown in FIG. 25 , a wireless power feeding system 3E differs from the wireless power feeding system 3 according to the first embodiment in that a power receiving terminal 2E is provided instead of the power receiving terminal 2 according to the first embodiment.

[0145] The power receiving terminal 2E differs from the power receiving terminal 2 in that it further includes a plurality of (two in FIG. 25 ) voltage adjustment circuits 28 that correspond one-to-one to a plurality of (two in FIG. 25 ) power receiving circuits 21. The two voltage adjustment circuits 28 include a first voltage adjustment circuit 28a and a second voltage adjustment circuit 28b. The first voltage adjustment circuit 28a is connected between the output terminals of the first power receiving circuit 21a and the DC output unit 24. The second voltage adjustment circuit 28b is connected between the output terminals of the second power receiving circuit 21b and the DC output unit 24.

[0146] Each of the plurality of voltage adjustment circuits 28 is, for example, a DC-DC converter.

[0147] (2) Advantages Like the wireless power feeding system 3 according to the first embodiment, the wireless power feeding system 3E according to the ninth embodiment can increase the received power and improve the power efficiency at the power receiving terminal 2E.

[0148] Furthermore, since the wireless power supply system 3E according to the ninth embodiment includes a plurality of voltage adjustment circuits 28, backflow between the plurality of power receiving circuits 21 can be suppressed even if the controllability of the plurality of power transmitting circuits 11 by the controller 12 is reduced.

[0149] Tenth Embodiment The basic configuration of a wireless power supply system 3 according to a tenth embodiment is the same as that of the wireless power supply system 3 according to the first embodiment, and therefore will not be illustrated or described below.

[0150] In the tenth embodiment, when the controller 12 controls the movement system 50 to move the power transmitting coil 10 to a position facing the power receiving coil 20, the controller 12 performs control to align the winding axis B10 of the power transmitting coil 10 with the winding axis B20 of the power receiving coil 20, as shown in Fig. 26 , and control to misalign the winding axis B10 of the power transmitting coil 10 with the winding axis B20 of the power receiving coil 20, as shown in Fig. 27 . Fig. 28 shows the relationship between the misalignment / coil radius between the power transmitting coil 10 and the power receiving coil 20, normalized by the coil radius, and power efficiency. The coil radius is the radius of each of the power transmitting coil 10 and the power receiving coil 20. In this embodiment, the controller 12 can change the power efficiency by changing the misalignment.

[0151] In this embodiment, the controller 12 shifts the position of the transmitting coil 10 relative to the receiving coil 20 connected to the receiving circuit 21 with the higher output voltage so that the output voltage of the first receiving circuit 21a and the output voltage of the second receiving circuit 21b are the same, thereby weakening the coupling between the transmitting coil 10 and the receiving coil 20.

[0152] In this embodiment, when there are two power transmitting circuits 11, as in a wireless power feeding system 3F shown in Fig. 29 , the degree of freedom in adjusting the output voltage of the power receiving circuit 21 increases. In the power transmitter 1F in Fig. 29 , the movement system 50 of the power transmitter 1 of embodiment 1 is illustrated as two movement mechanisms 18. The two movement mechanisms 18 include a first movement mechanism 18a that moves the first power transmitting coil 10a and a second movement mechanism 18b that moves the second power transmitting coil 10b.

[0153] 30 , in a power transmitter 1G having a configuration in which one power transmission circuit 11 distributes power to two power transmission coils 10 and the frequency and power of each power transmission coil 10 cannot be changed, the power efficiency can be changed by controlling the positional deviation, thereby making it possible to adjust the output voltages of the two power receiving circuits 21 to be the same. This makes it possible to prevent backflow from occurring between the multiple power receiving circuits 21.

[0154] (Embodiment 11) Hereinafter, a wireless power feeding system 3H according to embodiment 11 will be described with reference to Fig. 31. Regarding the wireless power feeding system 3H according to embodiment 11, components similar to those of the wireless power feeding system 3C according to embodiment 7 (see Fig. 17) are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0155] (1) Configuration The wireless power supply system 3H differs from the wireless power supply system 3C according to the seventh embodiment in that the second communication circuit 26 is configured to wirelessly transmit the number of the power receiving coils 20 of the power receiving terminal 2C to the first communication circuit 16 by wireless signal.

[0156] (2) Advantages In the wireless power feeding system 3H according to the eleventh embodiment, step S10 is not required in the operation (control algorithm) of the controller 12 described in the flowchart of Fig. 6 above, the control algorithm is simplified, and it is possible to shorten the time until charging of the battery of the power receiving terminal 2C starts. Also, the power receiving terminal 2R shown in Fig. 32 above may be configured to wirelessly transmit a wireless signal W2 including information on the number of power receiving coils 20 and the output voltage of the power receiving circuit 21 from the second communication circuit 26 to the first communication circuit 16 of the power transmitter 1C.

[0157] (Other Modifications) The above-described first to eleventh embodiments are merely examples of various embodiments of the present disclosure. The above-described first to eleventh embodiments can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved.

[0158] For example, the rectifier circuit 211 of the power receiving terminal 2 may be a full-wave rectifier circuit in which four diodes are bridge-connected, or may be a half-wave rectifier circuit.

[0159] (Aspects) The present specification discloses the following aspects.

[0160] A wireless power feeding system (3; 3A; 3B; 3C; 3D; 3E; 3F; 3G; 3H) according to a first aspect includes a power transmitter (1; 1A; 1B; 1C; 1F; 1G) and a power receiving terminal (2; 2A; 2B; 2C; 2D; 2E). The power receiving terminal (2; 2A; 2B; 2C; 2D; 2E) is fed with power from the power transmitter (1; 1A; 1B; 1C; 1F; 1G). The power transmitter (1; 1A; 1B; 1C; 1F; 1G) includes a plurality of power transmitting coils (10), a plurality of power transmitting circuits (11), and a controller (12). The plurality of power transmitting circuits (11) correspond one-to-one to the plurality of power transmitting coils (10) and supply transmission power to a corresponding one of the plurality of power transmitting coils (10). The controller (12) controls the multiple power transmission circuits (11). Each of the multiple power transmission circuits (11) outputs AC power to a corresponding one of the multiple power transmission coils (10). The power receiving terminal (2) has multiple power receiving coils (20), multiple power receiving circuits (21), and a DC output unit (24). The multiple power receiving coils (20) receive AC power from an opposing one of the multiple power transmission coils (10). The multiple power receiving circuits (21) correspond one-to-one to the multiple power receiving coils (20) and convert AC power received by a corresponding one of the multiple 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 plurality of power receiving circuits (21). The controller (12) acquires information on the output voltage of each of the plurality of power receiving circuits (21) through a wireless signal (W2) from each of the plurality of power receiving circuits (21), and controls at least one of the frequency and power of the power transmission radio waves of each of the plurality of power transmitting circuits (11) so that the output voltages of the plurality of power receiving circuits (21) are the same.

[0161] According to this aspect, it is possible to increase the received power and improve the power efficiency at the power receiving terminal (2; 2A; 2B; 2C; 2D; 2E).

[0162] In the wireless power supply system (3) according to the second aspect, in the first aspect, the power receiving terminal (2) transmits a wireless signal (W2) from each of the plurality of power receiving circuits (21) to the controller (12).

[0163] According to this aspect, since there is no need for each of the plurality of power transmission circuits (11) to receive the wireless signal (W2), it is possible to reduce the size and weight of the power transmitter (1).

[0164] In a wireless power feeding system (3A) according to a third aspect, in the first aspect, each of the plurality of power transmitting circuits (11) further includes a first communication circuit (16). Each of the plurality of power receiving circuits (21) further includes a second communication circuit (26). The power receiving terminal (2A) transmits a wireless signal (W2) from the second communication circuit (26) of each of the plurality of power receiving circuits (21) to the first communication circuit (16) of each of the plurality of power transmitting circuits (11). The controller (12) acquires information on the output voltage of each of the plurality of power receiving circuits (21) from the first communication circuit (16) of each of the plurality of power transmitting circuits (11).

[0165] According to this aspect, each of the plurality of power receiving circuits (21) of the power receiving terminal (2A) can communicate with a corresponding one of the plurality of power transmitting circuits (11).

[0166] In a wireless power supply system (3A) according to a fourth aspect, in the first aspect, each of the plurality of power transmitting circuits (11) further includes a first voltage measurement circuit (13), a first current measurement circuit (14), and a first communication circuit (16). The first voltage measurement circuit (13) measures an input voltage of the power transmitting circuit (11). The first current measurement circuit (14) measures an input current of the power transmitting circuit (11). Each of the plurality of power receiving circuits (21) further includes a second voltage measurement circuit (22), a second current measurement circuit (23), and a second communication circuit (26). The second voltage measurement circuit (22) measures an output voltage of the power receiving circuit (21). The second current measurement circuit (23) measures an output current of the power receiving circuit (21). Each of the multiple power receiving circuits (21) transmits a wireless signal (W2) including data on a measured voltage value from the second voltage measurement circuit (22) and data on a measured current value from the second current measurement circuit (23) to a first communication circuit (16) of a corresponding one of the multiple power transmitting circuits (11) from the second communication circuit (26). The controller (12) calculates the transmitted power using the measured voltage value data acquired from the first voltage measurement circuit (13) and the measured current value data acquired from the first current measurement circuit (14). The controller (12) calculates the received power using the measured voltage value data and the measured current value data transmitted from the second communication circuit (26) to the first communication circuit (16). The controller (12) calculates the power efficiency using the transmitted power and the received power. The controller (12) controls the frequency of the transmitted radio waves to maximize the power efficiency.

[0167] According to this aspect, power efficiency can be maximized, so that power transmission can be reduced and power consumption can be reduced.

[0168] In a wireless power supply system (3B) according to a fifth aspect, in the first aspect, each of the plurality of power receiving circuits (21) includes a modulation circuit (27) for transmitting a wireless signal (W2) via a corresponding one of the plurality of power receiving coils (20). Each of the plurality of power transmitting circuits (11) includes a demodulation circuit (17) for receiving the wireless signal (W2) via a corresponding one of the plurality of power transmitting coils (10).

[0169] 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.

[0170] In a wireless power supply system (3B) according to a sixth aspect, in the fifth aspect, each of the plurality of power transmitting circuits (11) further includes a first voltage measurement circuit (13) and a first current measurement circuit (14). The first voltage measurement circuit (13) measures an input voltage of the power transmitting circuit (11). The first current measurement circuit (14) measures an input current of the power transmitting circuit (11). Each of the plurality of power receiving circuits (21) further includes a second voltage measurement circuit (22) and a second current measurement circuit (23). The second voltage measurement circuit (22) measures an output voltage of the power receiving circuit (21). The second current measurement circuit (23) measures an output current of the power receiving circuit (21). Each of the plurality of power receiving circuits (21) transmits a wireless signal (W2) from a modulation circuit (27) to a demodulation circuit (17) of a corresponding one of the plurality of power transmitting circuits (11). The wireless signal (W2) includes data on the measured voltage value from the second voltage measurement circuit (22) and data on the measured current value from the second current measurement circuit (23). The controller (12) calculates input power using the measured voltage value data acquired from the first voltage measurement circuit (13) and the measured current value data acquired from the first current measurement circuit (14). The controller (12) calculates output power using the measured voltage value data and measured current value data transmitted from the modulation circuit (27) to the demodulation circuit (17). The controller (12) calculates power efficiency using the input power and output power, and controls the frequency of the power transmission radio waves to maximize power efficiency.

[0171] According to this aspect, power efficiency can be maximized, so that power transmission can be reduced and power consumption can be reduced.

[0172] A power receiving terminal (2; 2A; 2B; 2C; 2D; 2E) according to a seventh aspect is supplied with power by a power transmitter (1; 1A; 1B; 1C; 1F; 1G) having a plurality of power transmitting coils (10). The power receiving terminal (2; 2A; 2B; 2C; 2D; 2E) includes a plurality of power receiving coils (20), a plurality of power receiving circuits (21), and a DC output unit (24). 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 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 side output terminals of the plurality of power receiving circuits (21). The second DC output terminal (242) is a power receiving terminal (2; 2A; 2B; 2C; 2D; 2E) to which the low potential side output terminals of the plurality of power receiving circuits (21) are commonly connected, and transmits information on the output voltage of each of the plurality of power receiving circuits (21) to the power transmitter (1; 1A; 1B; 1C; 1F; 1G) via a wireless signal (W2) from each of the plurality of power receiving circuits (21).

[0173] According to this aspect, it is possible to increase the received power and improve the power efficiency at the power receiving terminal (2; 2A; 2B; 2C; 2D; 2E).

[0174] A power transmitter (1; 1A; 1B; 1C; 1F; 1G) according to an eighth aspect wirelessly transmits power to a power receiving terminal (2; 2A; 2B; 2C; 2D; 2E). The power transmitter (1; 1A; 1B; 1C; 1F; 1G) includes a plurality of power transmission coils (10), a plurality of power transmission circuits (11), and a controller (12). 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 one of the plurality of power transmission coils (10). The controller (12) controls the plurality of power transmission circuits (11). Each of the plurality of power transmission circuits (11) outputs AC power to a corresponding one of the plurality of power transmission coils (10). The power receiving terminal (2; 2A; 2B; 2C; 2D; 2E) includes a plurality of power receiving coils (20), a plurality of power receiving circuits (21), and a DC output unit (24). 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) 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) 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 plurality of power receiving circuits (21). The controller (12) acquires information on the output voltage of each of the plurality of power receiving circuits (21) through a wireless signal (W2) from each of the plurality of power receiving circuits (21), and controls at least one of the frequency and power of the power transmission radio waves of each of the plurality of power transmitting circuits (11) so that the output voltages of the plurality of power receiving circuits (21) are the same.

[0175] According to this aspect, it is possible to increase the received power and improve the power efficiency at the power receiving terminal (2; 2A; 2B; 2C; 2D; 2E).

[0176] 1, 1A, 1B, 1C, 1F, 1G Power transmitter 10 Power transmitting coil 11 Power transmitting circuit 110 DC-AC conversion circuit 12 Controller 13 Voltage measurement circuit (first voltage measurement circuit) 14 Current measurement circuit (first current measurement circuit) 16 First communication circuit 17 Demodulation circuit 2, 2A, 2B, 2C, 2D, 2E Power receiving terminal 20 Power receiving coil 21 Power receiving circuit 211 Rectification circuit 22 Voltage measurement circuit (second voltage measurement circuit) 23 Current measurement circuit (second current measurement circuit) 24 DC output section 241 First DC output terminal 242 Second DC output terminal 25 Diode circuit 26 Second communication circuit 27 Modulation circuit 28 Voltage adjustment circuit 3, 3A, 3B, 3C, 3D, 3E, 3F, 3G, 3H Wireless power supply system W2 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 which 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; and a controller which controls the plurality of power transmitting circuits, wherein each of the plurality of power transmitting circuits outputs AC power to a corresponding one of the plurality of power transmitting coils; and the power receiving terminal comprises: a plurality of power receiving coils which receive AC power from an opposing power transmitting coil of the plurality of power transmitting coils; a plurality of power receiving circuits which correspond one-to-one to the plurality of power receiving coils and convert the AC power received by a corresponding one of the plurality of power receiving coils into DC power; and a DC output unit which includes 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, the controller acquires information on the output voltage of each of the plurality of power receiving circuits via a wireless signal from each of the plurality of power receiving circuits, and controls at least one of the frequency and power of the transmission radio waves of each of the plurality of power transmitting circuits so that the output voltages of the plurality of power receiving circuits are the same.

2. The wireless power supply system according to claim 1, wherein the power receiving terminal transmits the wireless signal from each of the plurality of power receiving circuits to the controller.

3. The wireless power supply system according to claim 1, wherein each of the plurality of power transmitting circuits further includes a first communication circuit, and each of the plurality of power receiving circuits further includes a second communication circuit, and the power receiving terminal transmits the wireless signal from the second communication circuit of each of the plurality of power receiving circuits to the first communication circuit of each of the plurality of power transmitting circuits, and the controller acquires information on the output voltage of each of the plurality of power receiving circuits from the first communication circuit of each of the plurality of power transmitting circuits.

4. Each of the plurality of power transmitting circuits further includes a first voltage measuring circuit that measures an input voltage of the power transmitting circuit, a first current measuring circuit that measures an input current of the power transmitting circuit, and a first communication circuit; each of the plurality of power receiving circuits further includes a second voltage measuring circuit that measures an output voltage of the power receiving circuit, a second current measuring circuit that measures an output current of the power receiving circuit, and a second communication circuit; each of the plurality of power receiving circuits transmits a wireless signal including data on a measured voltage value of the second voltage measuring circuit and data on a measured current value of the second current measuring circuit from the second communication circuit to the first communication circuit of a corresponding power transmitting circuit among the plurality of power transmitting circuits; the controller calculates input power using the measured voltage value data acquired from the first voltage measuring circuit and the measured current value data acquired from the first current measuring circuit; calculates output power using the measured voltage value data and the measured current value data transmitted from the second communication circuit to the first communication circuit; and calculates power efficiency using the input power and the output power; The wireless power feeding system according to claim 1 , wherein a frequency of the power transmission radio wave is controlled so as to maximize the power efficiency.

5. The wireless power supply system according to claim 1, wherein each of the plurality of power receiving circuits includes a modulation circuit for transmitting the wireless signal via the corresponding one of the plurality of power receiving coils, and each of the plurality of power transmitting circuits includes a demodulation circuit for receiving the wireless signal via the corresponding one of the plurality of power transmitting coils.

6. Each of the plurality of power transmitting circuits further includes a first voltage measurement circuit that measures an input voltage of the power transmitting circuit and a first current measurement circuit that measures an input current of the power transmitting circuit; each of the plurality of power receiving circuits further includes a second voltage measurement circuit that measures an output voltage of the power receiving circuit and a second current measurement circuit that measures an output current of the power receiving circuit; each of the plurality of power receiving circuits transmits the wireless signal from the modulation circuit to the demodulation circuit of a corresponding power transmitting circuit among the plurality of power transmitting circuits, the wireless signal including measured voltage value data of the second voltage measurement circuit and measured current value data of the second current measurement circuit; the controller calculates input power using the measured voltage value data obtained from the first voltage measurement circuit and the measured current value data obtained from the first current measurement circuit; calculates output power using the measured voltage value data and the measured current value data transmitted from the modulation circuit to the demodulation circuit; calculates power efficiency using the input power and the output power; and controls the frequency of the power transmission radio wave so as to maximize the power efficiency. The wireless power supply system according to claim 5 .

7. A power receiving terminal that is powered by a power transmitter having a plurality of power transmitting coils, comprising: a plurality of power receiving coils; a plurality of power receiving circuits that correspond one-to-one to the plurality of power receiving coils and convert AC power received by a corresponding one of the plurality of power receiving coils into DC power; and a DC output unit that includes a first DC output terminal to which the high potential side output terminals of the plurality of power receiving circuits are commonly connected and a second DC output terminal to which the low potential side output terminals of the plurality of power receiving circuits are commonly connected; and the power receiving terminal transmits information about the output voltage of each of the plurality of power receiving circuits to the power transmitter by wireless signal from each of the plurality of power receiving circuits.

8. A power transmitter that wirelessly transmits power to a power receiving terminal, comprising: a plurality of power transmitting coils; a plurality of power transmitting circuits that 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; and a controller that controls the plurality of power transmitting circuits, wherein each of the plurality of power transmitting circuits outputs AC power to a corresponding one of the plurality of power transmitting coils; and the power receiving terminal comprises: a plurality of power receiving coils that receive AC power from an opposing power transmitting coil of the plurality of power transmitting coils; a plurality of power receiving circuits that correspond one-to-one to the plurality of power receiving coils and convert the AC power received by a corresponding one of the plurality of power receiving coils into DC power; and a DC output unit that includes 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, The controller acquires information on the output voltage of each of the plurality of power receiving circuits via a wireless signal from each of the plurality of power receiving circuits, and controls at least one of the frequency and power of the transmission radio waves of each of the plurality of power transmitting circuits so that the output voltages of the plurality of power receiving circuits are the same.

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