Power transmission device

Abstract

To improve power feeding efficiency to a power reception device by a power transmission device.SOLUTION: A non-contact power feeding system includes a power reception device and a power transmission device. A relative position of the power transmission device to the power reception device is fixed. The power transmission device includes a power transmission conversion unit, a power transmission antenna, and a power transmission control device. The power transmission control device switches a power transmission mode. The power transmission mode includes a normal output mode and a limited mode. The limited mode limits power transmission more than the normal output mode. The power transmission control device includes a storage unit. The storage unit stores appropriate power supply information in a case where surrounding environment of the power transmission device and the power reception device is in a steady state assumed in advance. The power transmission control device acquires power supply information in a peripheral environment when power transmission is performed. The power transmission control device determines whether or not power supply information is different from proper power supply information. When it is determined that the power supply information is different from the proper power supply information, the power transmission control device sets the power transmission mode to the limited mode.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a power transmission device.

Background Art

[0002] The non-contact power supply system disclosed in Patent Document 1 includes a power transmission device and a power reception device. The power transmission device transmits power by non-contact power supply. The power reception device receives the power transmitted from the power transmission device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, the power transmission device can select the optimal power supply path among a plurality of power supply paths depending on whether there are obstacles between the power transmission device and the power reception device. However, depending on the position of the obstacle and the type of the obstacle, it may not be possible to select the optimal power supply path. In this case, the power supply efficiency may decrease depending on the selected power supply path.

Means for Solving the Problems

[0005] The power transmission device for solving the above problems is a radial power transmission device with a fixed relative position to the power receiving device. The power transmission device includes a power transmission unit that transmits power to the power receiving device by non-contact power supply, a storage unit that stores appropriate power supply information in the case of a steady state assumed in advance for the surrounding environment of the power transmission device and the power receiving device, and a power transmission control device that switches the power transmission mode of the power transmission unit. The power transmission mode includes a normal output mode and a restricted mode in which the transmitted power is limited compared to the normal output mode. The power transmission control device acquires power supply information in the surrounding environment when performing the power transmission, determines whether the power supply information is different from the appropriate power supply information, and when it is determined that the power supply information is different from the appropriate power supply information, sets the power transmission mode to the restricted mode, and when it is determined that the power supply information is not different from the appropriate power supply information, sets the power transmission mode to the normal output mode.

[0006] When the relative position between the power receiving device and the power transmission device is fixed, the appropriate power supply information in the case of a steady state of the surrounding environment can be grasped in advance. When the surrounding environment becomes non-steady due to the influence of obstacles or the like, the power supply information and the appropriate power supply information will be different. Then, since the power transmission control device sets the power transmission mode to the restricted mode, the transmitted power will be limited compared to the case where the power transmission mode is the normal output mode. That is, when power transmission cannot be performed efficiently, the transmitted power will be limited. Thereby, the power supply efficiency from the power transmission device to the power receiving device can be increased.

[0007] Regarding the above power transmission device, the power transmission device may be provided in the same space as the power receiving device. When the power transmission device and the power receiving device are provided in the same space, it is difficult for an obstacle to be located between the power transmission device and the power receiving device. Thereby, a decrease in the power supply efficiency from the power transmission device to the power receiving device can be suppressed.

[0008] Regarding the above power transmission device, when the number of consecutive determinations that the power supply information is different from the appropriate power supply information reaches a specified number, the power transmission control device may update the appropriate power supply information.

[0009] Depending on changes in the surrounding environment of the power receiving device and the power transmitting device, the steady state may change. When the number of consecutive determinations that the power supply information differs from the appropriate power supply information reaches a specified number, it is considered that the steady state has changed, and the power transmission control device updates the appropriate power supply information. As a result, even when the steady state changes, power can be transmitted from the power transmitting device to the power receiving device.

Effects of the Invention

[0010] According to the present invention, the power supply efficiency from the power transmitting device to the power receiving device can be increased.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0012] An embodiment of the power transmitting device will be described. <Vehicle> As shown in FIG. 1, the vehicle 10 includes a passenger compartment A1. The passenger compartment A1 is a space where people can enter and exit. The vehicle 10 includes a first seat 13 and a second seat 15. The first seat 13 is the frontmost seat. The first seat 13 includes a backrest 14. The backrest 14 is tiltable in the front-rear direction of the vehicle 10. The second seat 15 is a seat provided behind the first seat 13. The second seat 15 includes a backrest 16. The backrest 16 is tiltable in the front-rear direction of the vehicle 10. The first seat 13 and the second seat 15 are reclining seats. A non-contact power supply system 20 is provided in the vehicle 10.

[0013] <Non-contact Power Supply System> The non-contact power supply system 20 includes a power receiving device 21 and a power transmitting device 31. The power receiving device 21 may be single or plural. The power transmitting device 31 may be single or plural. The power transmitting device 31 is of a radiation type. As the radiation type power transmitting device 31, for example, a microwave type, a laser type, and an ultrasonic type can be used. In this embodiment, the microwave type power transmitting device 31 will be taken as an example for explanation. The non-contact power supply system 20 is a system in which the power transmitting device 31 performs non-contact power supply to the power receiving device 21 using a power transmission signal W1. The power transmission signal W1 is a microwave.

[0014] <Power Receiving Device> As shown in FIG. 2, the power receiving device 21 includes a power receiving antenna 22, a power receiving conversion unit 23, a power receiving storage unit 24, a power receiving control device 25, and a power receiving communication unit 28. The power receiving device 21 is, for example, an electrical component of the vehicle 10. Examples of the power receiving device 21 include a lighting device and an audio device. The power receiving device 21 is provided inside the vehicle compartment A1. In the example shown in FIG. 1, the power receiving device 21 is provided at the bottom 12 of the vehicle 10 between the first seat 13 and the second seat 15. The power receiving device 21 may be provided at the headrest of the first seat 13, the headrest of the second seat 15, the center console, the luggage space, or the trunk room.

[0015] <Power Receiving Antenna> The power receiving antenna 22 is configured to be able to receive the power transmission signal W1. As the power receiving antenna 22, for example, a monopole antenna, a dipole antenna, a helical antenna, a parabolic antenna, or an antenna array including a plurality of antennas can be used. The power receiving antenna 22 converts the power transmission signal W1 into AC power. The power receiving antenna 22 is configured to be able to transmit and receive a data signal W2. The power receiving antenna 22 is configured to be able to transmit a beacon signal W3. The power receiving antenna 22 that receives the power transmission signal W1, the antenna that transmits and receives the data signal W2, and the antenna that transmits the beacon signal W3 may be provided separately.

[0016] <Power receiving conversion unit> The power receiving conversion unit 23 converts the AC power output from the power receiving antenna 22 into power receiving power. The power receiving power is the power obtained by the power receiving device 21 from the power transmission signal W1. The power receiving power is DC power. The specific embodiment of the power receiving conversion unit 23 is arbitrary, but for example, it includes a rectifier circuit and a smoothing circuit.

[0017] <Power receiving and storage unit> The power receiving and storage unit 24 is the power source of the power receiving device 21. As the power receiving and storage unit 24, for example, a secondary battery such as a lithium-ion battery or a capacitor can be used. The power receiving and storage unit 24 stores part or all of the power receiving power converted by the power receiving conversion unit 23. In this way, power reception by the power receiving device 21 using the power transmission signal W1 is performed.

[0018] <Power receiving control device> The power receiving control device 25 includes a processor 26 and a storage unit 27. The storage unit 27 includes a RAM (Random Access Memory) and a ROM (Read Only Memory). The storage unit 27 stores program codes or instructions configured to cause the processor 26 to execute processing. The storage unit 27, that is, the computer-readable medium, includes any available medium accessible by a general-purpose or dedicated computer. The power receiving control device 25 may be configured by a hardware circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The power receiving control device 25, which is a processing circuit, may include one or more processors operating according to a computer program, one or more hardware circuits such as an ASIC or an FPGA, or a combination thereof.

[0019] <Power receiving communication unit> The power receiving communication unit 28 communicates with the power transmission device 31 by transmitting and receiving the data signal W2. The power receiving communication unit 28 demodulates the data signal W2 received by the power receiving antenna 22 and outputs it to the power receiving control device 25. Further, the power receiving communication unit 28 transmits, from the power receiving antenna 22, a data signal W2 that has been modulated based on the data output by the power receiving control device 25. The communication mode using the data signal W2 is arbitrary, and examples include those conforming to any communication standard such as Bluetooth (registered trademark), Wi-Fi, ZigBee (registered trademark), etc.

[0020] <Power transmission device> The power transmission device 31 performs non-contact power supply to the power receiving device 21 using the power transmission signal W1. The power transmission device 31 includes a power transmission conversion unit 32, a power transmission antenna 33, a power transmission communication unit 34, and a power transmission control device 35. The power transmission device 31 is provided inside the vehicle compartment A1. It can be said that the power transmission device 31 and the power receiving device 21 are provided in the same space. The power transmission device 31 is provided on the ceiling 11 of the vehicle 10. The relative position of the power transmission device 31 with respect to the power receiving device 21 is fixed.

[0021] <Power transmission conversion unit> The power transmission conversion unit 32 converts the power supplied from the power source 40 into an electrical signal corresponding to the power transmission signal W1 and outputs it. The electrical signal can adopt any form such as voltage, current, power, etc. The specific configuration of the power transmission conversion unit 32 is arbitrary, but for example, it includes a circuit including a switching element such as a chopper circuit. Through the control of the switching element of the power transmission conversion unit 32, the power transmission conversion unit 32 outputs the DC power supplied from the power source 40 as an electrical signal of AC power. That is, the power transmission conversion unit 32 has a function as a DC / AC inverter.

[0022] <Power source> The power source 40 is mounted on the vehicle 10. Examples of the power source 40 include an auxiliary battery that supplies power to electrical components. If the vehicle 10 is an electric vehicle, a traction battery that supplies power to the traction motor may be used as the power source 40. Also, as the power source 40, a power source provided for the power transmission device 31 can be used. A generator provided in the vehicle 10 can also be used as the power source 40. The power source 40 may be a combination of the above-described power sources.

[0023] <Power transmission antenna> The power transmission antenna 33 is configured to be able to transmit a power transmission signal W1 to the power reception device 21. The power transmission antenna 33 converts an electrical signal output from the power transmission conversion unit 32 into a power transmission signal W1 and transmits it. As the power transmission antenna 33, for example, a monopole antenna, a dipole antenna, a helical antenna, a parabolic antenna, or an antenna array including a plurality of antennas can be used. The power transmission antenna 33 of the present embodiment is a phased array antenna including a plurality of antennas. The power transmission antenna 33 converts the power output from the power transmission conversion unit 32 into a power transmission signal W1 and transmits it wirelessly. Thereby, the power transmission device 31 supplies power for power transmission to the power reception device 21. The power for power transmission is the power transmitted as the power transmission signal W1. Also, the power transmission antenna 33 is configured to be able to transmit and receive a data signal W2. The power transmission antenna 33 is configured to be able to receive a beacon signal W3. The power transmission antenna 33 that transmits the power transmission signal W1, the antenna that transmits and receives the data signal W2, and the antenna that receives the beacon signal W3 may be provided separately.

[0024] <Power transmission communication unit> The power transmission communication unit 34 communicates with the power reception device 21 by transmitting and receiving the data signal W2. The power transmission communication unit 34 demodulates the data signal W2 received by the power transmission antenna 33 and outputs it toward the power transmission control device 35. The power transmission communication unit 34 transmits a data signal W2 that has been modulated based on data output from the power transmission control device 35 from the power transmission antenna 33. Thereby, the power transmission device 31 and the power reception device 21 are configured to be able to communicate with each other via the data signal W2.

[0025] <Power transmission control device> The power transmission control device 35 includes a processor 36 and a storage unit 37. The hardware configuration of the power transmission control device 35 is the same as that of the power reception control device 25, for example.

[0026] <Appropriate power supply information> The appropriate power supply information D1 is stored in the storage unit 37. When the power transmission device 31 includes an auxiliary storage device, the appropriate power supply information D1 may be stored in the auxiliary storage device. Examples of the auxiliary storage device include a hard disk drive, a solid state drive, and a flash memory. In this case, the auxiliary storage device is a storage unit that stores the appropriate power supply information D1.

[0027] The appropriate power supply information D1 is power supply information in a steady state where the surrounding environment of the power transmission device 31 and the power reception device 21 is assumed in advance. The steady state means that there are no obstacles temporarily existing in the surrounding environment of the power transmission device 31 and the power reception device 21. The obstacles in this embodiment are objects that can cause non-contact power supply obstacles. The obstacles include people. For example, when a person gets into the passenger compartment A1 and thus the person exists between the power transmission device 31 and the power reception device 21, the person can temporarily become a non-contact power supply obstacle. Thus, a state in which the power supply from the power transmission device 31 to the power reception device 21 is inhibited by a person is different from the steady state. Examples of the steady state can include an ideal state where there are no obstacles between the power transmission device 31 and the power reception device 21. Depending on the constraints on the arrangement states of the power transmission device 31 and the power reception device 21, there may always be obstacles between the power transmission device 31 and the power reception device 21. Thus, a state in which the surrounding environment of the power transmission device 31 and the power reception device 21 always includes existing obstacles is the steady state. The steady state can also be said to be a state in which the power supply path is stably determined.

[0028] The appropriate power supply information D1 includes appropriate power supply path information and appropriate power reception power information. The appropriate power supply path information is information indicating the appropriate power supply path, which is the power supply path in the steady state. The appropriate power supply path information can be obtained by the power transmission control device 35 calculating the power supply path after determining the relative positions of the power transmission device 31 and the power reception device 21. For example, after determining the relative positions of the power transmission device 31 and the power reception device 21, the power reception device 21 is made to transmit a power supply request signal in the steady state. When the power transmission control device 35 receives the power supply request signal with the power transmission antenna 33, it calculates the power supply path. The power supply path can be calculated from the arrival angle of the power supply request signal, the phase of the power supply request signal, and the reception intensity of the power supply request signal. When a phased array antenna is used as the power transmission antenna 33, when the power supply request signal is received by a plurality of antennas, the phase of the power supply request signal is different for each antenna. The arrival angle of the power supply request signal can be calculated from this phase. Then, the power transmission control device 35 stores, in the storage unit 37 as the appropriate power supply path information, the information indicating the appropriate power supply path that is the power supply path calculated in the steady state.

[0029] The appropriate power reception power information is information indicating the appropriate power reception power. The appropriate power reception power is the power value of the received power obtained by the power reception device 21 when the power transmission device 31 transmits the power transmission signal W1 via the appropriate power supply path. The appropriate power reception power information can be obtained by the power transmission control device 35 acquiring from the power reception device 21 the power value of the received power when the power transmission device 31 transmits the power transmission signal W1 via the appropriate power supply path. For example, after determining the relative positions of the power transmission device 31 and the power reception device 21, the power transmission device 31 is made to transmit the power transmission signal W1. The power reception device 21 measures the power value of the received power obtained by the power transmission signal W1. The power reception device 21 transmits a data signal W2 including the power value to the power transmission device 31. The power transmission control device 35 stores, in the storage unit 37 as the appropriate power reception power information, the information indicating the power value acquired from this data signal W2.

[0030] <Control performed by the power transmission control device> The power transmission control device 35 can adjust the transmitted power. The power transmission control device 35 can control the transmitted power, for example, by controlling the power transmission antenna 33. When a phased array antenna is used as the power transmission antenna 33, the transmitted power can be adjusted by adjusting the number of antennas for power transmission among the plurality of antennas. The adjustment of the transmitted power may be performed by adjusting the power input to the power transmission antenna 33 by controlling the power transmission conversion unit 32. It can be said that the power transmission control device 35 can adjust the transmitted power by controlling at least one of the power transmission conversion unit 32 and the power transmission antenna 33. The power transmission conversion unit 32 and the power transmission antenna 33 are power transmission units.

[0031] <Power transmission mode> The power transmission control device 35 can switch the power transmission mode of the power transmission unit. The power transmission mode includes a normal output mode and a restricted mode. The normal output mode is a mode in which the transmitted power is not restricted. In the case of the normal output mode, for example, a predetermined transmitted power is output. The magnitude of the transmitted power may change according to the power input from the power source 40. The restricted mode is a mode in which the transmitted power is more restricted than the normal output mode. The restriction of the transmitted power includes a mode in which no power is transmitted. The restricted mode of the present embodiment is a stop mode in which no power is transmitted. During the stop mode, no power is transmitted, but part of the operation of the power transmission control device 35 continues. Examples of the operation of the power transmission control device 35 that continues even during the stop mode include transmission and reception of the data signal W2, calculation regarding the power transmission direction for transmitting the power transmission signal W1, and storage in the storage unit 37 of the history regarding communication and calculation results. Then, the power transmission control device 35 adjusts the transmitted power according to the power transmission mode. Hereinafter, the switching control performed in the non-contact power supply system 20 for switching the power transmission mode will be described. The switching control includes power reception device side control performed by the power reception device 21 and power transmission device side control performed by the power transmission device 31.

[0032] <Power reception device side control> The power reception device side control performed by the power reception device 21 will be described. The power reception device side control is repeatedly executed at a predetermined control cycle.

[0033] As shown in FIG. 3, in step S1, the power reception control device 25 transmits a power transmission request signal. This power transmission request signal is transmitted as a beacon signal W3. The power transmission request signal is a signal for requesting power transmission to the power transmission device 31.

[0034] Next, in step S2, the power reception control device 25 determines whether power reception power has been obtained. When a power transmission signal W1 is transmitted from the power transmission device 31 in response to the power transmission request signal, the power reception power can be obtained from the power transmission signal W1. The determination in step S2 can also be said to be a determination as to whether the power transmission device 31 has transmitted the power transmission signal W1. If the determination result in step S2 is negative, the power reception control device 25 returns to the process of step S1. If the determination result in step S2 is positive, the power reception control device 25 performs the process of step S3.

[0035] In step S3, the power reception control device 25 measures the power reception power. Thereby, the power reception control device 25 can obtain the power value of the power reception power. The power reception power can be measured, for example, by providing a current sensor and a voltage sensor in the power reception conversion unit 23.

[0036] Next, in step S4, the power reception control device 25 transmits a data signal W2. This data signal W2 includes information indicating the power value of the power reception power measured in step S3. After finishing the process of step S4, the power reception control device 25 finishes the power reception device side control.

[0037] <Power Transmission Device Side Control> The power transmission device side control performed by the power transmission device 31 will be described. The power transmission device side control is repeatedly executed at a predetermined control cycle.

[0038] As shown in FIG. 4, in step S11, the power transmission control device 35 determines whether a power transmission request signal has been received. If the determination result in step S11 is negative, the power transmission control device 35 makes the determination in step S11 again. If the determination result in step S11 is positive, the power transmission control device 35 performs the process of step S12.

[0039] In step S12, the power transmission control device 35 calculates a power supply path from the power transmission request signal received in step S11. The calculation of the power supply path is performed by the same method as the calculation of the appropriate power supply path. That is, the power supply path can be calculated from the arrival angle, phase, and received power of the power transmission request signal received in step S11. The power supply path calculated in step S12 is the power supply path in the surrounding environment when performing power transmission.

[0040] Next, in step S13, the power transmission control device 35 reads the appropriate power supply information D1 from the storage unit 37. Next, in step S14, the power transmission control device 35 determines whether the power supply path calculated in step S12 is different from the appropriate power supply path. Specifically, the power transmission control device 35 determines whether the difference between the power supply path calculated in step S12 and the appropriate power supply path is within the allowable range. The allowable range is set so as to allow a slight error due to measurement error or the like. For example, an upper threshold value and a lower threshold value are set for the appropriate power supply path. Then, the range between the upper threshold value and the lower threshold value is set as the allowable range. The upper threshold value is, for example, the appropriate power supply path + a predetermined value. The lower threshold value is, for example, the appropriate power supply path - a predetermined value. The predetermined value used for setting the upper threshold value and the lower threshold value is set to a value that can allow an error due to measurement error or the like as described above. Also, the predetermined value may be set in consideration of the average fluctuation of the arrival angle, phase, and received power of the power transmission request signal. The predetermined value can be arbitrarily set, for example, in the range of 1% to 20% of the appropriate power supply path. When the difference between the power supply path and the appropriate power supply path is within the allowable range, the power transmission control device 35 determines that the power supply path and the appropriate power supply path are not different. When the difference between the power supply path and the appropriate power supply path is not within the allowable range, the power transmission control device 35 determines that the power supply path and the appropriate power supply path are different. If the determination result in step S14 is negative, the power transmission control device 35 performs the process of step S15. If the determination result in step S14 is positive, the power transmission control device 35 performs the process of step S17.

[0041] In step S15, the power transmission control device 35 sets the power transmission mode to the normal output mode. As a result, the power transmission signal W1 is transmitted from the power transmission device 31. Next, in step S16, the power transmission control device 35 determines whether the received power is different from the appropriate received power. When the power transmission signal W1 is transmitted in step S15, the power receiving device 21 transmits a data signal W2 including information indicating the power value of the received power. The power transmission control device 35 determines whether the power value of the received power obtained from this data signal W2 is different from the appropriate received power. Specifically, the power transmission control device 35 determines whether the difference between the power value of the received power acquired from the data signal W2 and the appropriate received power is within the allowable range. The allowable range is set to allow a slight error due to measurement error or the like. When the difference between the power value of the received power and the appropriate received power is within the allowable range, the power transmission control device 35 determines that the received power and the appropriate received power are not different. When the difference between the power value of the received power and the appropriate received power is not within the allowable range, the power transmission control device 35 determines that the received power and the appropriate received power are different. If the determination result in step S16 is affirmative, the power transmission control device 35 performs the process of step S18. If the determination result in step S16 is negative, the power transmission control device 35 ends the power transmission device side control.

[0042] In step S17, the power transmission control device 35 determines whether or not the number of consecutive determinations that the power supply path calculated in step S12 is different from the proper power supply path has reached a specified number. The power transmission control device 35 counts the number of affirmative determinations each time the determination result in step S14 is affirmative. When the determination result in step S14 is negative, the power transmission control device 35 resets the number of affirmative determinations. When the number of affirmative determinations reaches the specified number, the power transmission control device 35 determines that the number of consecutive determinations that the power supply path calculated in step S12 is different from the proper power supply path has reached the specified number. As the specified number, any value can be set. For example, when there are obstacles in the surrounding environment of the power transmission device 31 and the power receiving device 21, the specified number is set to the number of determinations that can determine that a time has elapsed such that the obstacles can be regarded as always existing. When the determination result in step S17 is negative, the power transmission control device 35 performs the process of step S18. When the determination result in step S17 is affirmative, the power transmission control device 35 performs the process of step S19.

[0043] In step S18, the power transmission control device 35 sets the power transmission mode to the stop mode. As a result, the power transmission signal W1 is no longer transmitted from the power transmission device 31. In step S19, the power transmission control device 35 updates the proper power supply information D1. For example, the power transmission control device 35 sets the power supply path calculated in step S12 as the proper power supply path. Then, the power transmission control device 35 sets the power value of the received power obtained by the power receiving device 21 by transmitting the power transmission signal W1 through the proper power supply path as the proper charging power.

[0044] <Function> The function of this embodiment will be described. When the relative positions of the power receiving device 21 and the power transmitting device 31 are fixed, it is possible to grasp in advance the appropriate power supply information D1 in a steady state of the surrounding environment. When the surrounding environment between the power receiving device 21 and the power transmitting device 31 becomes non-steady due to the influence of obstacles or the like, the power supply information and the appropriate power supply information D1 will be different. For example, as shown in FIG. 5, when the backrest 14 of the first seat 13 is reclined, the backrest 14 is positioned between the power transmitting device 31 and the power receiving device 21. As a result, the difference between the power supply path and the appropriate power supply path increases due to the change in the power supply path. Also, the difference between the power value of the received power and the appropriate received power increases. Similarly, when a person M1 sits on the second seat 15, the person M1 is positioned between the power transmitting device 31 and the power receiving device 21. The same can be said in this case. Thus, when the power supply information and the appropriate power supply information D1 become different, the power transmission control device 35 sets the power transmission mode to the stop mode.

[0045] <Effect> The effects of the present embodiment will be described. (1) When the power transmission control device 35 determines that the power supply information and the appropriate power supply information D1 are different, it sets the power transmission mode to the stop mode. The transmitted power will be limited as compared with the case where the power transmission mode is the normal output mode. When power transmission cannot be performed efficiently, the transmitted power will be limited. Thereby, the power supply efficiency from the power transmitting device 31 to the power receiving device 21 can be increased. Note that the power supply efficiency is the ratio of the received power to the transmitted power.

[0046] (2) The power transmitting device 31 and the power receiving device 21 are provided in the same space. When the power transmitting device 31 and the power receiving device 21 are provided in different spaces, obstacles that attenuate the power transmission signal W1 are likely to be positioned between the power transmitting device 31 and the power receiving device 21. For example, when the power transmitting device 31 and the power receiving device 21 are provided in different spaces, walls that define the respective spaces or a part of the vehicle 10 are positioned between the power transmitting device 31 and the power receiving device 21 as obstacles. On the other hand, when the power transmitting device 31 and the power receiving device 21 are provided in the same space, it is difficult for obstacles to be positioned between the power transmitting device 31 and the power receiving device 21. Thereby, a decrease in the power supply efficiency from the power transmitting device 31 to the power receiving device 21 can be suppressed.

[0047] (3) The power transmission device 31 and the power reception device 21 are provided in the same space. Since the power transmission signal W1 is transmitted in the space where the power transmission device 31 is provided, leakage of the power transmission signal W1 to the outside of the space where the power transmission device 31 is provided can be suppressed. In the case of the embodiment, leakage of the power transmission signal W1 to the outside of the passenger compartment A1 can be suppressed. Thereby, human exposure due to leakage of the power transmission signal W1 to the outside of the space where the power transmission device 31 is provided can be suppressed.

[0048] (4) When the number of consecutive determinations that the power supply path and the proper power supply path are different reaches the specified number, the power transmission control device 35 updates the proper power supply information D1. The steady state may change due to changes in the surrounding environment of the power reception device 21 and the power transmission device 31. For example, when an obstacle always exists between the power reception device 21 and the power transmission device 31, the existence of the obstacle becomes the steady state. When the number of consecutive determinations that the power supply path and the proper power supply path are different reaches the specified number, it can be regarded that the steady state has changed. Then, the power transmission control device 35 updates the proper power supply information D1. Thereby, power transmission from the power transmission device 31 to the power reception device 21 can be performed even when the steady state changes.

[0049] (5) The power transmission control device 35 calculates the power supply path from the power transmission request signal. The power transmission control device 35 grasps the power value of the received power from the data signal W2. Then, the power transmission control device 35 sets the power transmission mode to the stop mode according to the power supply path and the power value of the received power. The power transmission control device 35 can set the power transmission mode to the stop mode without using a sensor.

[0050] (6) When a person M1 exists between the power transmission device 31 and the power reception device 21, the power transmission mode is set to the stop mode. Compared with the case where the power transmission mode is the normal output mode, human exposure due to the power transmission signal W1 can be suppressed.

[0051] (7) Since the power transmission device 31 can supply power to the power reception device 21, there is no need to connect the power reception device 21 and the power source 40 by wiring. Therefore, it is not necessary to route the wiring to connect the power reception device 21 and the power source 40.

[0052] (8) The power transmission device 31 is provided on the ceiling 11. By providing the power transmission device 31 on the ceiling 11, it is possible to suppress the leakage of the power transmission signal W1 from the window to the outside of the passenger compartment A1. (Modified Example) The embodiment can be implemented with the following modifications. The embodiment and the following modified examples can be implemented in combination with each other as long as they do not technically conflict.

[0053] · The proper power supply path may be either the phase of the power transmission request signal or the arrival angle of the power transmission request signal. In this case, the power supply path calculated by the power transmission control device 35 from the power transmission request signal also changes in accordance with the proper power supply path.

[0054] · It may be possible for the user to determine whether or not to update the proper power supply information D1. For example, a selection of whether or not to update the proper power supply information D1 may be presented on a display unit visible to the user. The user selects whether or not to update the proper power supply information D1 using an input device. The display unit may be provided in the vehicle 10, or may be provided in a portable communication terminal possessed by the user. The input device may be, for example, a touch panel or a physical button.

[0055] · The power reception device 21 may be newly added. For example, a child seat equipped with the power reception device 21 may be newly added. In this case, the power transmission control device 35 acquires the proper power supply information D1 of the newly added power reception device 21. Then, the power transmission control device 35 stores the acquired proper power supply information D1 in the storage unit 37. In this case, the power transmission control device 35 can set the power transmission mode to the stop mode when there is a person in the child seat.

[0056] · When the number of consecutive determinations that the received power is different from the appropriate received power reaches a specified number, the power transmission control device 35 may update the appropriate power supply information D1. · The power transmission device 31 and the power reception device 21 may be provided in different spaces.

[0057] · The power transmission control device 35 does not necessarily have to update the appropriate power supply information D1. That is, the power transmission control device 35 does not necessarily have to perform the processes of step S17 and step S19. In this case, if the determination result in step S14 is affirmative, the power transmission control device 35 performs the process of step S18.

[0058] ·The comparison between the appropriate power supply information D1 and the power supply information may be performed by a sensor. As the sensor, for example, a camera can be used. As the camera, for example, a monocular camera, a stereo camera, and a ToF (Time of Flight) camera can be used. The camera is arranged to be able to image the surrounding environment of the power transmission device 31 and the power reception device 21. As the appropriate power supply information D1 in this case, for example, the image data obtained from the camera in the steady state can be cited. When performing power transmission, the power transmission control device 35 acquires the image data that is the power supply information from the camera. The power transmission control device 35 may compare the image data with the image data obtained from the camera in the steady state. The comparison between the image data is performed, for example, by comparing the feature points based on the luminance information. When an obstacle exists between the power transmission device 31 and the power reception device 21, a change occurs in the image data that becomes the appropriate power supply information D1. Therefore, the power transmission control device 35 can calculate the difference between the appropriate power supply information D1 and the power supply information by comparing the image data. The appropriate power supply information D1 may be the coordinate data of the surrounding objects in the steady state. The coordinate data of the surrounding objects in the steady state can be calculated using the image data acquired from the camera in the steady state. When performing power transmission, the power transmission control device 35 acquires the image data from the camera. The power transmission control device 35 calculates the coordinate data from the image data. When an obstacle exists between the power transmission device 31 and the power reception device 21, the coordinate data due to the obstacle is generated. Therefore, the power transmission control device 35 can calculate the difference between the appropriate power supply information D1 and the power supply information by comparing the coordinate data.

[0059] As the sensor, a biological detection sensor, an ultrasonic sensor, etc. may be used. In this case, when a living body or an obstacle exists between the power transmission device 31 and the power reception device 21, the power transmission control device 35 may set the power transmission mode to the stop mode.

[0060] ·The power reception device 21 does not have to transmit a power transmission request signal. The appropriate power supply path is stored in the storage unit 37 of the power transmission control device 35. Therefore, the power transmission device 31 can transmit the power transmission signal W1 using the appropriate power supply path without calculating the power supply path from the power transmission request signal.

[0061] · The power transmission device 31 may transmit an activation request signal to the power reception device 21. The activation request signal is a signal that requests activation of the power reception device 21 when the power reception device 21 is in the sleep state. The sleep state of the power reception device 21 is a state in which a part of the functions of the power reception device 21 is restricted. Even when the power reception device 21 is in the sleep state, the power reception device 21 transmits the data signal W2. When the power transmission device 31 does not receive the data signal W2 that responds to the activation request signal or the power transmission request signal, the power transmission control device 35 changes the power transmission mode to the stop mode.

[0062] · The power transmission device 31 may transmit a power transmission trial signal to the power reception device 21. The power transmission trial signal is a signal that requests activation of the power reception device 21 when the power reception device 21 is in the stop state. The stop state of the power reception device 21 is a state in which the functions of the power reception device 21 are more restricted than in the sleep state. When the power reception device 21 is in the stop state, the power reception device 21 does not transmit the data signal W2. When the power transmission device 31 does not receive the data signal W2 that responds to the power transmission trial signal, the power transmission control device 35 changes the power transmission mode to the stop mode.

[0063] · The data signal W2 and the power transmission request signal transmitted from the power reception device 21 may include identification information. The identification information is a unique ID code set in the power reception device 21. In this case, the power transmission device 31 may perform power transmission only to the power reception device 21 with the pre - authenticated identification information. Also, when the non - contact power supply system 20 includes a plurality of power reception devices 21, the appropriate power supply information D1 can be stored in the storage unit 37 for each power reception device 21 in association with the identification information. Then, the power transmission control device 35 can compare the appropriate power supply information D1 and the power supply information for each power reception device 21.

[0064] · The appropriate power supply information D1 may be either appropriate power supply path information or appropriate received power information. When the appropriate power supply information D1 is only the appropriate power supply path information, the determination in step S16 may not be performed. When the appropriate power supply information D1 is only the appropriate received power information, the determination in step S14 may not be performed.

[0065] · The non-contact power supply system 20 may be used in buildings such as factories, homes, commercial facilities, and public facilities. Examples of the power source 40 in this case include a utility power supply and a power generation device such as a solar power generation device.

[0066] · The restricted mode may be a low output mode. The low output mode is a power transmission mode that transmits a lower power transmission power than the normal output mode. The low output mode may be a mode that lowers the power value of the power transmission power compared to the normal output mode. The low output mode may be a mode that lowers the transmission frequency of the power transmission signal W1 compared to the normal output mode.

[0067] · The space where the power transmission device 31 and the power reception device 21 are provided may be a space where entry by a third party is restricted. By providing the power transmission device 31 and the power reception device 21 in the same space, leakage of the power transmission signal W1 outside the space where the power transmission device 31 is provided can be suppressed. Even when a power reception device 21 not intended by the user is installed outside the space, reception by the power reception device 21 can be suppressed.

Explanation of Signs

[0068] D1… Appropriate power supply information A1… The passenger compartment which is a space 21… Power reception device 31… Power transmission device 35… Power transmission control device 37… Storage unit

Claims

1. A radial power transmission device with a fixed relative position to a power receiving device, wherein the power transmission device comprises a power transmission unit that transmits power to the power receiving device by non-contact power supply, a storage unit that stores appropriate power supply information in a steady state where the surrounding environment of the power transmission device and the power receiving device is assumed in advance, and a power transmission control device that switches the power transmission mode of the power transmission unit, wherein the power transmission mode includes a normal output mode and a restricted mode in which the transmitted power is limited compared to the normal output mode, and the power transmission control device acquires power supply information in the surrounding environment when performing the power transmission, determines whether the power supply information is different from the appropriate power supply information, when it is determined that the power supply information is different from the appropriate power supply information, sets the power transmission mode to the restricted mode, when it is determined that the power supply information is not different from the appropriate power supply information, sets the power transmission mode to the normal output mode, and updates the appropriate power supply information when the number of consecutive determinations that the power supply information is different from the appropriate power supply information reaches a specified number. A power transmission device.

2. The power transmission device according to claim 1, wherein the power transmission device is provided in the same space as the power receiving device.

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