JP2014023414A - Power reception device and vehicle comprising the same, power transmission device, and power transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a foreign matter between a power transmission device and a power reception device and to suppress power loss due to the foreign matter detection in a power transmission system for transmitting power from the power transmission device to the power reception device in a non-contact manner.SOLUTION: A vehicle 100 comprises a power reception unit 110 and foreign matter detection sensors 150A and 150B. A power transmission device 200 comprises a high-frequency power source 220 and a power transmission unit 230. The power reception unit 110 receives power transmitted from the power transmission unit 230 in a non-contact manner. The foreign matter detection sensors 150A and 150B detect a foreign matter between the power transmission unit 230 and the power reception unit 110. The foreign matter detection sensors 150A and 150B start in conjunction with a start of power transmission from the power transmission unit 230 to the power reception unit 110, and stop in conjunction with a stop of power transmission.

Description

  The present invention relates to a power receiving device, a vehicle including the power receiving device, a power transmitting device, and a power transmission system, and more particularly, to a power receiving device including a detection device that detects a foreign object between the power transmitting device and the power receiving device, and a vehicle including the power receiving device. As well as the power transmission system.

  Japanese Patent Application Laid-Open No. 11-321497 (Patent Document 1) discloses a safe driving support device that detects and alerts a driver when an animal or the like enters the lower part of a vehicle when the vehicle is parked or stopped. In this safe driving support device, an ultrasonic sensor is disposed on the lower surface of the vehicle body. Then, based on the comparison result between the reflected sound wave waveform immediately after the vehicle stops and the reflected sound wave waveform measured sequentially after the stop, it is detected whether an animal or the like has entered the lower part of the vehicle (see Patent Document 1).

  On the other hand, in recent years, as a power transmission method applicable to an electric vehicle such as an electric vehicle or a hybrid vehicle, contactless power transmission without using a power cord or a power cable has attracted attention. As this non-contact power transmission technique, for example, techniques such as power transmission using electromagnetic induction, power transmission using microwaves, and so-called resonance type power transmission are known.

JP 11-321497 A JP 2011-217460 A

  In the non-contact power transmission described above, it is conceivable that foreign matter (thing that should not exist) enters between the power transmission device and the power reception device. Therefore, it is necessary to appropriately detect foreign matter that has entered between the power transmission device and the power reception device. However, the power consumption increases by providing a detection device for detecting such a foreign object. In particular, when the detection device is mounted on a vehicle, there is an extremely high demand for suppressing power loss. Therefore, it is important to reduce the power consumption by the detection device, but this point is not particularly examined in the patent document.

  Therefore, an object of the present invention is to detect foreign matter between a power transmitting device and a power receiving device in a power receiving device that receives power transmitted from the power transmitting device in a non-contact manner and a vehicle including the power receiving device. It is to suppress power loss.

  Another object of the present invention is to suppress power loss due to foreign object detection while realizing foreign object detection between the power transmission apparatus and the power reception apparatus in a power transmission apparatus that sends power to the power reception apparatus in a contactless manner. is there.

  Another object of the present invention is to reduce power loss due to foreign object detection while realizing foreign object detection between the power transmission apparatus and the power reception apparatus in a power transmission system that transmits power from the power transmission apparatus to the power reception apparatus in a contactless manner. It is to suppress.

  According to this invention, the power receiving device is a power receiving device that receives the power transmitted from the power transmitting device in a contactless manner, and includes the power receiving unit and the detection device. The power receiving unit receives the power transmitted from the power transmission device in a contactless manner. The detection device detects a foreign object between the power transmission device and the power reception device. The detection device starts in conjunction with the start of power reception by the power reception unit, and stops in conjunction with the end of power reception.

  Preferably, the power receiving device further includes a communication unit. The communication unit communicates with the power transmission device. The detection device is activated when communication with the power transmission device is established by the communication unit.

Preferably, the detection device stops when communication with the power transmission device by the communication unit is interrupted.
Preferably, the detection device operates by receiving the power received by the power receiving unit.

  Preferably, the detection device is electrically connected to a power line from which the power received by the power receiving unit is output, and operates by receiving power from the power line.

  Preferably, the detection device includes another power reception unit. Another power receiving unit receives the power transmitted from the power transmission device in a contactless manner. The detection device is operated by the power received by the other power receiving unit.

Preferably, the detection device detects intrusion of a foreign substance based on whether or not the detection information changes with time.
Preferably, the power receiving device is mounted on a vehicle. The detection device is installed on the lower surface of the vehicle body, and the detection range is set toward the ground facing the power reception unit.

Preferably, the detection device is an ultrasonic sensor.
Preferably, the difference between the natural frequency of the power reception unit and the natural frequency of the power transmission unit of the power transmission apparatus is ± 10% or less of the natural frequency of the power reception unit or the natural frequency of the power transmission unit.

Preferably, the coupling coefficient between the power reception unit and the power transmission unit of the power transmission device is 0.3 or less.
Preferably, the power reception unit receives power from the power transmission unit through at least one of a magnetic field formed between the power reception unit and the power transmission unit of the power transmission device and an electric field formed between the power reception unit and the power transmission unit. The magnetic field and the electric field are formed between the power reception unit and the power transmission unit, and vibrate at a specific frequency.

  According to the invention, the vehicle includes any one of the power receiving devices described above, the power storage device, and the electric motor. The power storage device stores the power received by the power receiving device. The electric motor generates a driving force by the electric power stored in the power storage device.

  Moreover, according to this invention, a power transmission apparatus is a power transmission apparatus which transmits electric power to a power receiving apparatus in a non-contact manner, and includes a power transmission unit and a detection apparatus. The power transmission unit transmits power to the power receiving device in a contactless manner. The detection device detects a foreign object between the power transmission device and the power reception device. The detection device starts in conjunction with the start of power transmission by the power transmission unit, and stops in conjunction with the end of power transmission.

  According to the invention, the power transmission system is a power transmission system that transmits power from the power transmission device to the power reception device in a contactless manner, and includes a power transmission unit, a power reception unit, and a detection device. The power transmission unit transmits power from the power transmission device to the power reception device in a contactless manner. The power receiving unit receives the power transmitted from the power transmission device in a contactless manner. The detection device detects a foreign object between the power transmission device and the power reception device. The detection device starts in conjunction with the start of power transmission from the power transmission device to the power reception device, and stops in conjunction with the stop of power transmission.

  In this invention, the detection apparatus which detects the foreign material between a power transmission apparatus and a power receiving apparatus is provided. Then, the detection device starts in conjunction with the start of power transmission from the power transmission device to the power reception device, and stops in conjunction with the stop of power transmission. As a result, the detection device consumes power only when power is transmitted from the power transmission device to the power reception device, which substantially requires foreign object detection, so that the power consumption of the detection device can be minimized. Therefore, according to the present invention, it is possible to suppress power loss due to foreign object detection while detecting foreign objects between the power transmission device and the power receiving device.

1 is an overall configuration diagram of a power transmission system according to Embodiment 1 of the present invention. It is a top view of the rear part of the vehicle shown in FIG. It is a functional block diagram of vehicle ECU shown in FIG. It is a flowchart for demonstrating the starting process of a foreign material detection sensor. It is a flowchart for demonstrating the stop processing of a foreign material detection sensor. It is an electric circuit diagram which implement | achieves non-contact electric power transmission in the electric power transmission system shown in FIG. It is a figure which shows the simulation model of an electric power transmission system. It is a figure which shows the relationship between the shift | offset | difference of the natural frequency of a power transmission part and a power receiving part, and electric power transmission efficiency. It is a graph which shows the relationship between the electric power transmission efficiency when changing an air gap in the state which fixed the natural frequency, and the frequency of the electric current supplied to a power transmission part. It is the figure which showed the relationship between the distance from an electric current source or a magnetic current source, and the intensity | strength of an electromagnetic field. FIG. 6 is an electric circuit diagram of a power transmission system in a second embodiment. 6 is an electric circuit diagram of a power transmission system according to Embodiment 3. FIG. It is a 1st figure for demonstrating arrangement | positioning of the foreign material detection sensor in a modification. It is a 2nd figure for demonstrating arrangement | positioning of the foreign material detection sensor in a modification. FIG. 6 is an overall configuration diagram of a power transmission system according to a fourth embodiment. FIG. 9 is an electric circuit diagram of a power transmission system according to a fifth embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Embodiment 1]
(overall structure)
1 is an overall configuration diagram of a power transmission system according to Embodiment 1 of the present invention. With reference to FIG. 1, the power transmission system includes a vehicle 100 and a power transmission device 200. Vehicle 100 includes a power reception unit 110, a rectification unit 120, a power storage device 130, a power generation unit 140, foreign matter detection sensors 150A and 150B, a vehicle ECU (Electronic Control Unit) 160, and a communication unit 170. Power transmission device 200 includes a high-frequency power source 220, a power transmission unit 230, a power supply ECU 240, and a communication unit 250.

  The power receiving unit 110 of the vehicle 100 receives the power transmitted from the power transmitting unit 230 of the power transmitting device 200 in a non-contact manner and outputs the power to the rectifying unit 120. In the first embodiment, power transmission unit 230 is provided in the ground or on the ground surface, and power reception unit 110 is provided at the lower part of the vehicle body at the rear of the vehicle. Note that the location of the power receiving unit 110 is not limited to this, and when the power transmitting unit 230 is provided in the ground or on the ground surface, the power receiving unit 110 may be provided in the lower part of the vehicle body at the front or center of the vehicle. .

  As an example, power reception unit 110 is configured by a resonance circuit including a coil and a capacitor. A specific configuration of the power reception unit 110 will be described later together with the power transmission unit 230 of the power transmission device 200.

  Rectifier 120 converts AC power received from power receiver 110 into DC power, and outputs the converted DC power to power storage device 130. The power storage device 130 is a rechargeable DC power supply, and is configured by a secondary battery such as lithium ion or nickel metal hydride. The power storage device 130 stores power output from the rectifying unit 120 and also stores power generated by the power generation unit 140. Then, the power storage device 130 supplies the stored power to the power generation unit 140. Note that a large-capacity capacitor can also be used as the power storage device 130.

  Power generation unit 140 generates a driving force for driving vehicle 100 using electric power stored in power storage device 130. Although not particularly illustrated, motive power generation unit 140 includes, for example, an inverter that receives electric power from power storage device 130, a motor driven by the inverter, a drive wheel driven by the motor, and the like. Power generation unit 140 may include a generator for charging power storage device 130 and an engine capable of driving the generator.

  Foreign object detection sensors 150 </ b> A and 150 </ b> B are sensors for detecting a foreign object between vehicle 100 and power transmission device 200. In addition, a foreign substance does not originally exist in the detection range of the foreign substance detection sensors 150A and 150B. Here, an animal or the like that exists between the vehicle 100 and the power transmission device 200 is assumed.

  As the foreign matter detection sensors 150A and 150B, various sensors that can detect foreign matter according to changes in detected information with time can be adopted. For example, sonar, pyroelectric sensor, radio wave sensor, optical sensor, etc. can be adopted. is there. Note that the sonar detects foreign matter using reflection of ultrasonic waves, and the pyroelectric sensor detects a change in the amount of infrared rays input to the pyroelectric element to detect the foreign matter. The radio wave sensor detects a foreign object based on a change in the reception intensity of the radio wave, and the optical sensor detects a foreign object by detecting a change in reflected light from the object.

  In the first embodiment, the foreign matter detection sensors 150A and 150B are provided on the lower surface of the vehicle body in response to the power transmission unit 230 of the power transmission device 200 being provided in the ground or on the ground surface and the power reception unit 110 being provided in the lower part of the vehicle body. Installed. Preferably, foreign matter detection sensors 150A and 150B are directed toward the ground facing power reception unit 110 (toward power transmission unit 230 of power transmission device 200), as shown in the plan view of FIG. The detection range is set. Such an arrangement makes it possible to reliably detect foreign matter that has entered between the power transmission unit 230 and the power reception unit 110 during power transmission from the power transmission unit 230 to the power reception unit 110 of the power transmission device 200.

  In the first embodiment, two foreign object detection sensors 150A and 150B are provided. However, the number of foreign object detection sensors is not limited to two, and may be one or three. There may be more than one. Further, the arrangement (including the detection range) of the foreign object detection sensor is not limited to the arrangement shown in FIGS. 1 and 2. For example, the foreign object detection sensors 150 </ b> A and 150 </ b> B May be arranged respectively. In the first embodiment, foreign matter detection sensors 150A and 150B receive operating power from an auxiliary power source (not shown).

  Referring again to FIG. 1, vehicle ECU 160 receives charging information related to a state of charge (SOC) of power storage device 130 from power storage device 130, and based on the received charging information, power storage device 200 by power transmission device 200. Control the charging of 130. When power transmission from the power transmission device 200 to the vehicle 100 is performed, the vehicle ECU 160 communicates with the power transmission device 200 through the communication unit 170 and exchanges various information for executing power transmission from the power transmission device 200 to the vehicle 100.

  Moreover, vehicle ECU160 controls the operation | movement of the foreign material detection sensors 150A and 150B. Specifically, vehicle ECU 160 outputs a start command to foreign matter detection sensors 150A and 150B in conjunction with the start of power reception by power reception unit 110, and issues a stop command to foreign matter detection sensors 150A and 150B in conjunction with the end of power reception. Output. Thereby, foreign matter detection sensors 150A and 150B are activated in conjunction with the start of power reception by power reception unit 110, and are stopped in conjunction with the end of power reception.

  In the first embodiment, when communication with the communication unit 250 of the power transmission device 200 is established by the communication unit 170, it is determined that power transmission from the power transmission device 200 to the vehicle 100 is started, and the foreign matter detection sensors 150A and 150B are to start. Further, when communication with the communication unit 250 of the power transmission device 200 by the communication unit 170 is interrupted, it is determined that power transmission from the power transmission device 200 to the vehicle 100 is completed, and the foreign matter detection sensors 150A and 150B are stopped.

  Note that the activation timing of the foreign matter detection sensors 150A and 150B may be when the power reception unit 110 actually receives power from the power transmission apparatus 200, as well as when communication between the communication units 170 and 250 is established. Alternatively, when a power supply switch (not shown) instructing power transmission from the power transmission device 200 to the vehicle 100 is turned on by the user, or when the power receiving unit 110 is aligned with the power transmission unit 230 of the power transmission device 200 (the power transmission device 200). It may be when the vehicle 100 is parked) or when the alignment is completed.

  Further, the stop timing of the foreign matter detection sensors 150A and 150B may be not only when the communication between the communication units 170 and 250 is interrupted, but also when the power reception from the power transmission device 200 by the power reception unit 110 actually ends. Alternatively, it may be when the power supply switch is turned off by the user or when the vehicle 100 starts running.

  Communication unit 170 is a communication interface for vehicle 100 to communicate with power transmission device 200. The communication unit 170 is configured to perform wireless communication with the communication unit 250 of the power transmission device 200.

  On the other hand, in power transmission device 200, high frequency power supply 220 receives power from system power supply 210, for example, and generates high frequency AC power. The power transmission unit 230 receives supply of high-frequency AC power from the high-frequency power source 220 and transmits power to the power reception unit 110 of the vehicle 100 in a contactless manner. As an example, the power transmission unit 230 is configured by a resonance circuit including a coil and a capacitor. A specific configuration of power transmission unit 230 will be described later together with power reception unit 110 of vehicle 100.

  The power supply ECU 240 controls the operation of the high frequency power supply 220 during power transmission from the power transmission device 200 to the vehicle 100. In addition, power supply ECU 240 communicates with vehicle 100 through communication unit 250 and exchanges various information for executing power transmission from power transmission device 200 to vehicle 100. Communication unit 250 is a communication interface for power transmission device 200 to communicate with vehicle 100, and is configured to perform wireless communication with communication unit 170 of vehicle 100.

(Configuration of vehicle ECU)
FIG. 3 is a functional block diagram of vehicle ECU 160 shown in FIG. Referring to FIG. 3, vehicle ECU 160 includes a communication control unit 162, a charge control unit 164, and a sensor control unit 166.

  The communication control unit 162 controls communication with the power transmission device 200 by the communication unit 170 (FIG. 1). Specifically, when power transmission from power transmission device 200 to vehicle 100 is requested, communication control unit 162 causes communication unit 170 to establish communication between communication unit 170 and communication unit 250 of power transmission device 200. To control. Note that, regarding a power transmission request from the power transmission device 200 to the vehicle 100, for example, when a power switch (not shown) that instructs power transmission from the power transmission device 200 to the vehicle 100 is turned on by the user, It is determined that power transmission to vehicle 100 is requested. Alternatively, when the positioning of the power receiving unit 110 with respect to the power transmission unit 230 of the power transmission device 200 (the parking operation of the vehicle 100 with respect to the power transmission device 200) is started, or when the above alignment is completed, the vehicle 100 It is also possible that power transmission to is requested. Then, when communication is established between the communication units 170 and 250, the communication control unit 162 notifies the charge control unit 164 and the sensor control unit 166 to that effect.

  Further, the communication control unit 162 receives from the charging control unit 164 information related to a power transmission start command and a power transmission stop command from the power transmission device 200 to the vehicle 100, a power reception status (received power, voltage, current, etc.) in the vehicle 100, and the like. The communication unit 170 is controlled to transmit the received information to the power transmission device 200.

  Further, when the end of power transmission from the power transmission device 200 to the vehicle 100 is requested, the communication control unit 162 controls the communication unit 170 to end communication between the communication units 170 and 250. Note that, regarding a request for termination of power transmission from the power transmission device 200 to the vehicle 100, for example, when the power supply switch is turned off by the user or when the vehicle 100 starts a traveling operation, the power transmission device 200 transmits the vehicle 100. It is determined that the end of power transmission to is requested. Then, when communication between the communication units 170 and 250 is interrupted, the communication control unit 162 notifies the charge control unit 164 and the sensor control unit 166 to that effect.

  Charging control unit 164 controls the start and end of power transmission from power transmission device 200 to vehicle 100 and the charging of power storage device 130 by power transmission device 200. Specifically, charging control unit 164 outputs a power transmission start command to communication control unit 162 when a predetermined charging execution condition permitting charging of power storage device 130 by power transmitting device 200 is satisfied. Charging control unit 164 performs charging of power storage device 130 based on the detected values of SOC, charging voltage V, and charging power I of power storage device 130. Charging control unit 164 outputs a power transmission end command to communication control unit 162 when a predetermined charging end condition for ending charging of power storage device 130 is satisfied.

  In addition, the charging control unit 164 notifies the sensor control unit 166 that charging control is being performed, that is, while power transmission from the power transmission device 200 to the vehicle 100 is being performed.

  The sensor control unit 166 controls the operation of the foreign matter detection sensors 150A and 150B. Specifically, when receiving a notification from the communication control unit 162 that communication between the communication units 170 and 250 has been established, the sensor control unit 166 outputs an activation signal ACT to the foreign matter detection sensors 150A and 150B. As a result, the foreign matter detection sensors 150A and 150B are activated and actuated by receiving operating power from an auxiliary power source (not shown). In addition, when receiving a notification from the communication control unit 162 that the communication between the communication units 170 and 250 has been interrupted, the sensor control unit 166 outputs a stop signal STP to the foreign matter detection sensors 150A and 150B. Thereby, the foreign matter detection sensors 150A and 150B are stopped, and the power consumption by the foreign matter detection sensors 150A and 150B is eliminated.

(Foreign matter detection sensor start / stop processing)
FIG. 4 is a flowchart for explaining the activation processing of the foreign matter detection sensors 150A and 150B. Referring to FIG. 4, when the start of power transmission from power transmission device 200 to vehicle 100 is requested (YES in step SS10), the vehicle system is activated (step S20). When the vehicle system is activated, vehicle ECU 160 activates communication unit 170 (step S30).

  Then, when communication between communication unit 170 and communication unit 250 of power transmission device 200 is established (YES in step S40), vehicle ECU 160 activates foreign matter detection sensors 150A and 150B (step S50). As a result, the foreign matter detection sensors 150A and 150B operate in response to operating power and start detecting foreign matter.

  When foreign matter is detected by foreign matter detection sensors 150A and 150B (YES in step S60), vehicle ECU 160 determines whether or not charging (non-contact charging) of power storage device 130 by power transmission device 200 is being performed ( Step S70). If it is determined that charging is being performed (YES in step S70), vehicle ECU 160 stops charging power storage device 130 (step S80). That is, vehicle ECU 160 transmits a power transmission stop command to power transmission device 200 through communication unit 170. On the other hand, when it is determined in step S70 that charging is not being performed (NO in step S70), vehicle ECU 160 prohibits charging of power storage device 130. That is, transmission of a power transmission start command to the power transmission device 200 is prohibited. As a result, the vehicle 100 enters a charging standby state (step S90).

  When no foreign object is detected in step S60 (NO in step S60), vehicle ECU 160 determines whether or not foreign object detection sensors 150A and 150B have been stopped by the sensor stop process described below (step S100). If it is determined that foreign matter detection sensors 150A and 150B are stopped (YES in step S100), the process proceeds to step S110 and if foreign matter detection sensors 150A and 150B are determined to be operating ( In step S100, NO), the process is returned to step S60.

  FIG. 5 is a flowchart for explaining stop processing of the foreign matter detection sensors 150A and 150B. Referring to FIG. 5, vehicle ECU 160 determines whether or not the vehicle system is activated (step S210). If it is determined that the vehicle system is being activated (YES in step S210), vehicle ECU 160 determines whether communication between communication units 170 and 250 has been established (step S220).

  When it is determined that communication between communication units 170 and 250 has been established (YES in step S220), vehicle ECU 160 determines whether or not communication between communication units 170 and 250 has been terminated. (Step S230). When it is determined that communication between communication units 170 and 250 is interrupted (YES in step S230), vehicle ECU 160 stops foreign matter detection sensors 150A and 150B (step S240). As a result, the foreign matter detection sensors 150A and 150B end the detection of the foreign matter, and the power supply to the foreign matter detection sensors 150A and 150B is stopped.

(Circuit configuration of power transmission system)
Next, power transmission from the power transmission device 200 to the vehicle 100 will be described. FIG. 6 is an electric circuit diagram for realizing non-contact power transmission in the power transmission system shown in FIG. 1. The circuit configuration shown in FIG. 6 is an example, and the configuration for realizing non-contact power transmission is not limited to the configuration in FIG.

  Referring to FIG. 6, power receiving unit 110 of vehicle 100 includes a secondary coil 340 and a capacitor 350. The secondary coil 340 forms a resonance circuit together with the capacitor 350, and receives power transmitted from the power transmission unit 230 of the power transmission device 200 in a non-contact manner. Rectifier 120 rectifies the AC power received by secondary coil 340 and outputs the rectified power to power storage device 130. Although not particularly shown, a closed loop is formed by the secondary coil 340 and the capacitor 350, and a coil for taking out AC power received by the secondary coil 340 from the secondary coil 340 by electromagnetic induction and outputting it to the rectifying unit 120 is separately provided. It may be provided.

  On the other hand, in power transmission device 200, power transmission unit 230 includes a primary coil 330 and a capacitor 335. Primary coil 330 forms a resonance circuit together with capacitor 335, and transmits AC power supplied from high-frequency power source 220 to power receiving unit 110 in a contactless manner. Although not particularly illustrated, a coil that forms a closed loop with the primary coil 330 and the capacitor 335 and supplies AC power output from the high-frequency power source 220 to the primary coil 330 by electromagnetic induction may be separately provided.

  Capacitors 335 and 350 are provided to adjust the natural frequency of the resonance circuit, and when a desired natural frequency is obtained using the stray capacitances of the primary coil 330 and the secondary coil 340, The capacitor 335, 350 may be omitted.

  Note that a matching unit 240 may be provided between the high-frequency power source 220 and the power transmission unit 230 (not shown in FIG. 1). As an example, the matching unit 240 includes variable capacitors 310 and 315 and a coil 320. The matching unit 240 can change the impedance by changing the capacitance of the variable capacitors 310 and 315. By changing the impedance in the matching unit 240, the impedance of the power transmission device 200 can be matched with the impedance of the vehicle 100 (impedance matching). The high-frequency power source 220 may have an impedance matching function, and in that case, the matching unit 240 may be omitted.

  Hereinafter, non-contact power transmission from the power transmission unit 230 of the power transmission device 200 to the power reception unit 110 of the vehicle 100 will be described. In this power transmission system, the difference between the natural frequency of power transmission unit 230 and the natural frequency of power reception unit 110 is ± 10% or less of the natural frequency of power transmission unit 230 or the natural frequency of power reception unit 110. By setting the natural frequencies of the power transmission unit 230 and the power reception unit 110 in such a range, the power transmission efficiency can be increased. On the other hand, when the difference between the natural frequencies is larger than ± 10%, the power transmission efficiency is smaller than 10%, and the power transmission time becomes longer.

  The natural frequency of the power transmission unit 230 (power reception unit 110) is a vibration frequency when an electric circuit (resonance circuit) configured by the primary coil 330 and the capacitor 335 (secondary coil 340 and capacitor 350) freely vibrates. means. Note that the resonance frequency of the power transmission unit 230 (power reception unit 110) means that the braking force or electric resistance is zero in an electric circuit (resonance circuit) configured by the primary coil 330 and the capacitor 335 (secondary coil 340 and capacitor 350). This means the natural frequency.

  A simulation result obtained by analyzing the relationship between the natural frequency difference and the power transmission efficiency will be described with reference to FIGS. 7 and 8. FIG. 7 is a diagram illustrating a simulation model of the power transmission system. FIG. 8 is a diagram illustrating the relationship between the deviation of the natural frequencies of the power transmission unit and the power reception unit and the power transmission efficiency.

  With reference to FIG. 7, the power transmission system 389 includes a power transmission unit 390 and a power reception unit 391. The power transmission unit 390 includes a first coil 392 and a second coil 393. The second coil 393 includes a resonance coil 394 and a capacitor 395 provided in the resonance coil 394. The power receiving unit 391 includes a third coil 396 and a fourth coil 397. The third coil 396 includes a resonance coil 399 and a capacitor 398 connected to the resonance coil 399.

  The inductance of the resonance coil 394 is defined as an inductance Lt, and the capacitance of the capacitor 395 is defined as a capacitance C1. Further, the inductance of the resonance coil 399 is defined as an inductance Lr, and the capacitance of the capacitor 398 is defined as a capacitance C2. When each parameter is set in this way, the natural frequency f1 of the second coil 393 is expressed by the following equation (1), and the natural frequency f2 of the third coil 396 is expressed by the following equation (2).

f1 = 1 / {2π (Lt × C1) ^1/2 } (1)
f2 = 1 / {2π (Lr × C2) ^1/2 } (2)
Here, when the inductance Lr and the capacitances C1 and C2 are fixed and only the inductance Lt is changed, the relationship between the deviation of the natural frequency of the second coil 393 and the third coil 396 and the power transmission efficiency is shown in FIG. Show. In this simulation, the relative positional relationship between the resonance coil 394 and the resonance coil 399 is fixed, and the frequency of the current supplied to the second coil 393 is constant.

  In the graph shown in FIG. 8, the horizontal axis indicates the deviation (%) of the natural frequency, and the vertical axis indicates the power transmission efficiency (%) at a constant frequency. The deviation (%) in natural frequency is expressed by the following equation (3).

(Deviation of natural frequency) = {(f1−f2) / f2} × 100 (%) (3)
As is clear from FIG. 8, when the deviation (%) in the natural frequency is 0%, the power transmission efficiency is close to 100%. When the deviation (%) in natural frequency is ± 5%, the power transmission efficiency is about 40%. When the deviation (%) in natural frequency is ± 10%, the power transmission efficiency is about 10%. When the deviation (%) in natural frequency is ± 15%, the power transmission efficiency is about 5%. That is, the natural frequencies of the second coil 393 and the third coil 396 are set so that the absolute value (difference in natural frequency) of the deviation (%) of the natural frequency falls within a range of 10% or less of the natural frequency of the third coil 396. It can be seen that the power transmission efficiency can be increased to a practical level by setting. Furthermore, when the natural frequency of the second coil 393 and the third coil 396 is set so that the absolute value of the deviation (%) of the natural frequency is 5% or less of the natural frequency of the third coil 396, the power transmission efficiency is further increased. This is more preferable. The simulation software employs electromagnetic field analysis software (JMAG (registered trademark): manufactured by JSOL Corporation).

  Referring to FIG. 6 again, the power transmission unit 230 of the power transmission device 200 and the power reception unit 110 of the vehicle 100 receive power in a non-contact manner through at least one of a magnetic field and an electric field formed between the power transmission unit 230 and the power reception unit 110. Give and receive. A magnetic field and / or electric field formed between the power transmission unit 230 and the power reception unit 110 vibrates at a specific frequency. Then, power is transmitted from the power transmission unit 230 to the power reception unit 110 by causing the power transmission unit 230 and the power reception unit 110 to resonate with each other by an electromagnetic field.

  Here, a magnetic field having a specific frequency formed around the power transmission unit 230 will be described. The “magnetic field of a specific frequency” typically has a relationship with the power transmission efficiency and the frequency of the current supplied to the power transmission unit 230. First, the relationship between the power transmission efficiency and the frequency of the current supplied to the power transmission unit 230 will be described. The power transmission efficiency when power is transmitted from the power transmission unit 230 to the power reception unit 110 varies depending on various factors such as the distance between the power transmission unit 230 and the power reception unit 110. For example, the natural frequency (resonance frequency) of the power transmission unit 230 and the power reception unit 110 is f0, the frequency of the current supplied to the power transmission unit 230 is f3, and the air gap between the power transmission unit 230 and the power reception unit 110 is the air gap AG. And

  FIG. 9 is a graph showing the relationship between the power transmission efficiency when the air gap AG is changed and the frequency f3 of the current supplied to the power transmission unit 230 with the natural frequency f0 fixed. Referring to FIG. 9, the horizontal axis indicates the frequency f3 of the current supplied to the power transmission unit 230, and the vertical axis indicates the power transmission efficiency (%). The efficiency curve L1 schematically shows the relationship between the power transmission efficiency when the air gap AG is small and the frequency f3 of the current supplied to the power transmission unit 230. As shown in the efficiency curve L1, when the air gap AG is small, the peak of power transmission efficiency occurs at frequencies f4 and f5 (f4 <f5). When the air gap AG is increased, the two peaks when the power transmission efficiency is increased change so as to approach each other. As shown in the efficiency curve L2, when the air gap AG is larger than the predetermined distance, the power transmission efficiency has one peak, and the power transmission efficiency is obtained when the frequency of the current supplied to the power transmission unit 230 is the frequency f6. Becomes a peak. When the air gap AG is further increased from the state of the efficiency curve L2, the peak of power transmission efficiency is reduced as shown by the efficiency curve L3.

  For example, the following method can be considered as a method for improving the power transmission efficiency. As a first technique, the capacitance of the capacitors 335 and 350 is changed between the power transmission unit 230 and the power reception unit 110 by keeping the frequency of the current supplied to the power transmission unit 230 constant according to the air gap AG. A method of changing the characteristics of the power transmission efficiency in the network is conceivable. Specifically, the capacitances of the capacitors 335 and 350 are adjusted so that the power transmission efficiency reaches a peak in a state where the frequency of the current supplied to the power transmission unit 230 is constant. In this method, the frequency of the current flowing through the power transmission unit 230 and the power reception unit 110 is constant regardless of the size of the air gap AG. Note that, as a method of changing the characteristics of the power transmission efficiency, a method of using the matching unit 240 of the power transmission device 200, a method of using a converter provided between the rectifying unit 120 and the power storage device 130 in the vehicle 100, or the like. It is also possible to adopt.

  The second method is a method of adjusting the frequency of the current supplied to the power transmission unit 230 based on the size of the air gap AG. For example, when the power transmission characteristic is the efficiency curve L1, a current of frequency f4 or f5 is supplied to the power transmission unit 230. When the frequency characteristic is the efficiency curves L2 and L3, the current having the frequency f6 is supplied to the power transmission unit 230. In this case, the frequency of the current flowing through power transmission unit 230 and power reception unit 110 is changed in accordance with the size of air gap AG.

  In the first method, the frequency of the current flowing through the power transmission unit 230 is a fixed constant frequency, and in the second method, the frequency flowing through the power transmission unit 230 is a frequency that changes as appropriate depending on the air gap AG. A current having a specific frequency set so as to increase the power transmission efficiency is supplied to the power transmission unit 230 by the first method, the second method, or the like. When a current having a specific frequency flows through the power transmission unit 230, a magnetic field (electromagnetic field) that vibrates at a specific frequency is formed around the power transmission unit 230. The power receiving unit 110 receives power from the power transmitting unit 230 through a magnetic field that is formed between the power receiving unit 110 and the power transmitting unit 230 and vibrates at a specific frequency. Therefore, the “magnetic field oscillating at a specific frequency” is not necessarily a magnetic field having a fixed frequency. In the above example, focusing on the air gap AG, the frequency of the current supplied to the power transmission unit 230 is set. However, the power transmission efficiency depends on the horizontal direction of the power transmission unit 230 and the power reception unit 110. The frequency changes depending on other factors such as a deviation, and the frequency of the current supplied to the power transmission unit 230 may be adjusted based on the other factors.

  In the above description, a coil (for example, a helical coil) is used for the power transmission unit 230 and the power reception unit 110, but an antenna such as a meander line may be used instead of the coil. When an antenna such as a meander line is used, an electric field having a specific frequency flows through the power transmission unit 230, so that an electric field having a specific frequency is formed around the power transmission unit 230. And electric power transmission is performed between the power transmission part 230 and the power receiving part 110 through this electric field.

  In this power transmission system, power transmission and power reception efficiency are improved by using a near field (evanescent field) in which the “electrostatic magnetic field” of the electromagnetic field is dominant.

  FIG. 10 is a diagram showing the relationship between the distance from the current source or magnetic current source and the strength of the electromagnetic field. Referring to FIG. 10, the electromagnetic field is composed of three components. The curve k1 is a component that is inversely proportional to the distance from the wave source, and is referred to as a “radiated electromagnetic field”. A curve k2 is a component inversely proportional to the square of the distance from the wave source, and is referred to as an “induction electromagnetic field”. The curve k3 is a component inversely proportional to the cube of the distance from the wave source, and is referred to as an “electrostatic magnetic field”. When the wavelength of the electromagnetic field is “λ”, the distance at which the strengths of “radiation electromagnetic field”, “induction electromagnetic field”, and “electrostatic magnetic field” are substantially equal can be expressed as λ / 2π.

  The “electrostatic magnetic field” is a region where the intensity of the electromagnetic wave suddenly decreases with the distance from the wave source. In the power transmission system according to this embodiment, the near field (evanescent field) in which the “electrostatic magnetic field” is dominant. ) Is used to transmit energy (electric power). That is, in the near field where the “electrostatic magnetic field” is dominant, the power transmitting unit 230 and the power receiving unit 110 (for example, a pair of coils) having adjacent natural frequencies are resonated to transfer the power from the power transmitting unit 230 to the other power receiving unit 110. Transmit energy (electric power). Since this "electrostatic magnetic field" does not propagate energy far away, the resonance method transmits power with less energy loss than electromagnetic waves that transmit energy (electric power) by "radiant electromagnetic field" that propagates energy far away. be able to.

  As described above, in this power transmission system, power is transmitted in a non-contact manner between the power transmission unit 230 and the power reception unit 110 by causing the power transmission unit 230 and the power reception unit 110 to resonate with each other by an electromagnetic field. . Such an electromagnetic field formed between the power transmission unit 230 and the power reception unit 110 may be referred to as a near-field resonance (resonance) coupling field, for example. The coupling coefficient κ between the power transmission unit 230 and the power reception unit 110 is, for example, about 0.3 or less, and preferably 0.1 or less. As a matter of course, a range where the coupling coefficient κ is about 0.1 to 0.3 can also be adopted. The coupling coefficient κ is not limited to such a value, and may take various values that improve power transmission.

  Note that the coupling between the power transmission unit 230 and the power reception unit 110 in the power transmission is, for example, “magnetic resonance coupling”, “magnetic field (magnetic field) resonance coupling”, “magnetic field resonance (resonance) coupling”, “proximity” The field resonance (resonance) coupling, the electromagnetic field (electromagnetic field) resonance coupling, the electric field (electric field) resonance coupling, and the like. The “electromagnetic field (electromagnetic field) resonance coupling” means a coupling including any of “magnetic resonance coupling”, “magnetic field (magnetic field) resonance coupling”, and “electric field (electric field) resonance coupling”.

  When the power transmission unit 230 and the power reception unit 110 are formed of coils as described above, the power transmission unit 230 and the power reception unit 110 are coupled mainly by a magnetic field (magnetic field), and are referred to as “magnetic resonance coupling” or “magnetic field”. (Magnetic field) resonance coupling "is formed. As described above, an antenna such as a meander line can be used for the power transmission unit 230 and the power reception unit 110. In this case, the power transmission unit 230 and the power reception unit 110 mainly include an electric field (electric field). ) To form an “electric field (electric field) resonance coupling”.

  As described above, in the first embodiment, foreign matter detection sensors 150A and 150B that detect foreign matter between power transmission device 200 and vehicle 100 are provided. The foreign matter detection sensors 150A and 150B are activated in conjunction with the start of power transmission from the power transmission device 200 to the vehicle 100, and are halted in conjunction with the termination of power transmission. As a result, the foreign matter detection sensors 150A and 150B consume power only when power is transmitted from the power transmission device 200 to the vehicle 100, which substantially requires foreign matter detection, so the power consumption of the foreign matter detection sensors 150A and 150B is the minimum necessary. To the limit. Therefore, according to the first embodiment, it is possible to suppress power loss of vehicle 100 due to foreign object detection while realizing foreign object detection between power transmission device 200 and vehicle 100.

  In the first embodiment, the foreign matter detection sensors 150A and 150B are installed on the lower surface of the vehicle body and face the ground facing the power reception unit 110 (toward the power transmission unit 230 of the power transmission device 200). A detection range of 150B is set. Therefore, according to the first embodiment, it is possible to reliably detect foreign matter that has entered between power transmission unit 230 and power reception unit 110 during power transmission from power transmission device 200 to vehicle 100.

[Embodiment 2]
In the second embodiment, the foreign object detection sensor operates by receiving the power received by the power reception unit of the vehicle. As a result, the foreign object detection sensor operates only during actual power transmission from the power transmission device to the vehicle, and stops when power transmission from the power transmission device to the vehicle is not performed.

  FIG. 11 is an electric circuit diagram of the power transmission system according to the second embodiment. The electric circuit shown in FIG. 11 corresponds to FIG. 6 showing the electric circuit of the power transmission system in the first embodiment.

  Referring to FIG. 11, vehicle 100A in the second embodiment is different from vehicle 100 in the first embodiment in the power supply configuration of foreign object detection sensors 150A and 150B. That is, in the second embodiment, foreign object detection sensors 150A and 150B are electrically connected to a power line from which power received by power reception unit 110 is output. The foreign object detection sensors 150A and 150B operate by receiving a part of the received power when the power receiving unit 110 is receiving power from the power transmitting unit 230 of the power transmitting device 200.

  In FIG. 11, a configuration in which foreign matter detection sensors 150A and 150B are electrically connected to power line PL between rectifying unit 120 and power storage device 130 is representatively shown. The foreign matter detection sensors 150 </ b> A and 150 </ b> B may be electrically connected between the power receiving unit 110 and the rectifying unit 120.

  The other configuration of the power transmission system in the second embodiment is basically the same as the configuration of the power transmission system in the first embodiment.

  Although not particularly illustrated, a relay that is turned on when power storage device 130 is charged by power transmission device 200 is provided between power storage device 130 and power line PL, and power reception unit 110 receives power from power transmission unit 230. If not, the relay is turned off. Accordingly, the foreign matter detection sensors 150A and 150B operate by receiving power received by the power receiving unit 110 only when the power receiving unit 110 receives power (when the power transmission device 200 charges the power storage device 130). When power is not received, operating power is not supplied to the foreign matter detection sensors 150A and 150B.

  As described above, in the second embodiment, foreign object detection sensors 150A and 150B operate by receiving the power received by power reception unit 110. Thereby, during non-power transmission from power transmission device 200 to vehicle 100A, power is not supplied to foreign matter detection sensors 150A and 150B, and foreign matter detection sensors 150A and 150B are stopped. Therefore, according to the second embodiment, the power consumption of foreign matter detection sensors 150A and 150B can be suppressed to the minimum necessary while reliably detecting the foreign matter between power transmission device 200 and vehicle 100A.

  Further, according to the second embodiment, foreign matter detection sensors 150A and 150B are electrically disconnected from the auxiliary power supply, and therefore are displayed on foreign matter detection sensors 150A and 150B during power transmission from power transmission device 200 to vehicle 100A. It is possible to suppress high-frequency noise transmitted to the auxiliary power supply.

[Embodiment 3]
In the second embodiment, the foreign object detection sensor is operated by receiving the electric power received by the power receiving unit 110 of the vehicle. However, in the third embodiment, the foreign object detection sensor itself receives the electric power sent from the power transmission device. A power receiving unit for receiving power in a non-contact manner is separately provided. When the power is transmitted from the power transmission device to the vehicle, the foreign object detection sensor is operated by the power received by the power receiving unit provided separately from the power transmission device.

  FIG. 12 is an electric circuit diagram of the power transmission system according to the third embodiment. The electric circuit shown in FIG. 12 also corresponds to FIG. 6 showing the electric circuit of the power transmission system in the first embodiment.

  Referring to FIG. 12, vehicle 100B in the third embodiment includes foreign object detection sensors 150C and 150D instead of foreign object detection sensors 150A and 150B in the configuration of vehicle 100 in the first embodiment. The arrangement of the foreign matter detection sensors 150C and 150D is the same as that of the first embodiment.

  Each of foreign matter detection sensors 150C and 150D includes a power reception unit 180, a rectification unit 182 and a detection unit 184. The power receiving unit 180 is configured by a resonance circuit including a coil and a capacitor, for example, similarly to the power receiving unit 110, and receives power transmitted from the power transmitting unit 230 of the power transmitting device 200 in a non-contact manner and outputs the power to the rectifying unit 182.

  The rectifying unit 182 rectifies the AC power received by the power receiving unit 180 and outputs the rectified power to the detecting unit 184. The detection unit 184 operates by receiving the electric power output from the rectification unit 182, and detects a foreign object between the vehicle 100 </ b> B and the power transmission device 200. That is, detection unit 184 operates using the power received by power reception unit 180 from power transmission unit 230 when power transmission from power transmission device 200 to vehicle 100B is performed. The configuration of detection unit 184 is the same as that of foreign matter detection sensors 150A and 150B in the first embodiment.

  The other configuration of the power transmission system in the third embodiment is basically the same as the configuration of the power transmission system in the first embodiment.

  As described above, in the third embodiment, each of foreign matter detection sensors 150C and 150D includes power receiving unit 180, and is operated by the power received by power receiving unit 180. Thereby, during non-power transmission from power transmission device 200 to vehicle 100B, power is not supplied to foreign matter detection sensors 150C and 150D, and foreign matter detection sensors 150C and 150D are stopped. Therefore, according to the third embodiment, the power consumption of foreign matter detection sensors 150C and 150D can be suppressed to the minimum necessary while reliably detecting the foreign matter between power transmission device 200 and vehicle 100B.

  Also in the third embodiment, foreign matter detection sensors 150C and 150D are electrically disconnected from the auxiliary power supply, and therefore appear in foreign matter detection sensors 150C and 150D when power is transmitted from power transmission device 200 to vehicle 100B. Propagation of high frequency noise to the auxiliary power supply can be suppressed.

[Modification]
In this modification, an example in which the arrangement of the foreign object detection sensors is different from the above embodiments is shown.

  13 and 14 are diagrams for explaining the arrangement of the foreign object detection sensors in this modification. 13 and 14 correspond to FIGS. 1 and 2, respectively. Referring to FIGS. 13 and 14, foreign object detection sensor 150 </ b> A, corresponding to the fact that power transmission unit 230 of power transmission device 200 is provided in the ground or on the ground surface and power reception unit 110 is provided in the lower part of the vehicle body behind the vehicle. 150E and 150F are installed on the lower surface of the vehicle body at the rear of the vehicle.

  The detection ranges of the foreign matter detection sensors 150A, 150E, and 150F are all set toward the ground in the front direction of the vehicle, and at least the foreign matter detection sensor 150A at the center is on the ground facing the power receiving unit 110 (of the power transmission device 200). A detection range is set toward the power transmission unit 230). Although not particularly illustrated, the detection ranges of the foreign matter detection sensors 150E and 150F may be set toward the ground facing the power receiving unit 110.

  The configuration of the foreign matter detection sensors 150E and 150F is the same as that of the foreign matter detection sensor 150A. Further, as in the second embodiment, the foreign matter detection sensors 150A, 150E, and 150F may be electrically connected to a power line that outputs the power received by the power receiving unit 110. Further, the foreign object detection sensor 150C (150D) described in the third embodiment may be employed instead of each of the foreign object detection sensors 150A, 150E, and 150F.

[Embodiment 4]
In each of the above embodiments, the foreign object detection sensor is provided on the vehicle side, but the foreign object detection sensor may be provided on the power transmission apparatus side.

  FIG. 15 is an overall configuration diagram of a power transmission system according to the fourth embodiment. Referring to FIG. 15, the power transmission system includes a vehicle 100D and a power transmission device 200A. Vehicle 100D has a configuration that does not include foreign object detection sensors 150A and 150B with respect to vehicle 100 shown in FIG.

  Power transmission device 200 </ b> A further includes foreign matter detection sensors 260 </ b> A and 260 </ b> B, and includes power supply ECU 240 </ b> A instead of power supply ECU 240 in the configuration of power transmission device 200 shown in FIG. 1. Foreign object detection sensors 260 </ b> A and 260 </ b> B are sensors for detecting a foreign object between power transmission device 200 and vehicle 100. As the foreign matter detection sensors 260A and 260B, various sensors capable of detecting the foreign matter according to the change of the detected information with time can be employed. For example, a sonar, a pyroelectric sensor, a radio wave sensor, an optical sensor, or the like can be employed. is there.

  In the fourth embodiment, the foreign object detection sensors 260A and 260B are installed on the ground surface corresponding to the power transmission unit 230 being provided in the ground or on the ground surface and the power receiving unit 110 of the vehicle 100D being provided in the lower part of the vehicle body. Is done. Preferably, the detection ranges of the foreign matter detection sensors 260A and 260B are set in the foreign matter detection sensors 260A and 260B toward the upper portion of the power transmission unit 230. Such an arrangement makes it possible to reliably detect foreign matter that has entered between the power transmission unit 230 and the power reception unit 110 during power transmission from the power transmission unit 230 to the power reception unit 110.

  Also in the fourth embodiment, the number of foreign matter detection sensors is not limited to two, but may be one, or may be three or more. Further, the arrangement (including the detection range) of the foreign object detection sensors is not limited to the arrangement shown in FIG. 15. For example, the foreign object detection sensors 260 </ b> A and 260 </ b> B are respectively arranged on the left and right of the power transmission unit 230 with respect to the vehicle parking direction. You may arrange.

  Power supply ECU 240A controls the operation of high-frequency power supply 220 when power is transmitted from power transmission device 200A to vehicle 100D. The power supply ECU 240A controls the operation of the foreign matter detection sensors 260A and 260B. Specifically, power supply ECU 240A outputs a start command to foreign matter detection sensors 260A and 260B in conjunction with the start of power transmission by power transmission unit 230, and issues a stop command to foreign matter detection sensors 260A and 260B in conjunction with the end of power transmission. Output. As a result, the foreign matter detection sensors 260A and 260B are activated in conjunction with the start of power transmission by the power transmission unit 230 and stopped in conjunction with the end of power transmission.

  As an example, when communication with communication unit 170 of vehicle 100D is established by communication unit 250, foreign object detection sensors 260A and 260B are activated, and when communication with communication unit 170 of vehicle 100D is interrupted by communication unit 250, the foreign object is detected. It is assumed that the detection sensors 260A and 260B are stopped.

  Note that the activation timing of the foreign matter detection sensors 260A and 260B may be when power is actually transmitted from the power transmitting apparatus 200A to the power receiving unit 110 in addition to when communication between the communication units 250 and 170 is established. Alternatively, when a power switch (not shown) instructing power transmission from the power transmission device 200A to the vehicle 100D is turned on by the user, or when the power receiving unit 110 is aligned with the power transmission unit 230 (the vehicle 100D with respect to the power transmission device 200A). It may be when the parking operation) is started or when the alignment is completed.

  Further, the stop timing of the foreign matter detection sensors 260A and 260B may be when communication between the communication units 250 and 170 is interrupted, or when power transmission to the vehicle 100D by the power transmission unit 230 actually ends. Alternatively, it may be when the power supply switch is turned off by the user or when the vehicle 100D starts running.

  As described above, according to the fourth embodiment, the power consumption of the foreign matter detection sensors 260A and 260B can be minimized. As a result, it is possible to suppress power consumption accompanying foreign object detection while realizing foreign object detection between the power transmission device 200A and the vehicle 100D.

[Embodiment 5]
In the fifth embodiment, as in the fourth embodiment, the foreign object detection sensor is provided on the power transmission device side. The foreign object detection sensor operates by receiving electric power output from the high-frequency power source 220 during power transmission from the power transmission device to the vehicle. As a result, the foreign object detection sensor operates only during actual power transmission from the power transmission device to the vehicle, and stops when power transmission from the power transmission device to the vehicle is not performed.

  FIG. 16 is an electric circuit diagram of the power transmission system according to the fifth embodiment. The electrical circuit shown in FIG. 16 corresponds to FIG. 6 showing the electrical circuit of the power transmission system in the first embodiment.

  Referring to FIG. 16, power transmission device 200B according to the fifth embodiment is different in power supply configuration from power transmission device 200A according to the fourth embodiment and foreign matter detection sensors 260A and 260B. That is, in the fifth embodiment, the foreign matter detection sensors 260A and 260B are connected to the rectifying unit 270, and the rectifying unit 270 is electrically connected to a power line between the high frequency power supply 220 and the power transmitting unit 230. The foreign object detection sensors 260 </ b> A and 260 </ b> B operate by receiving a part of the power output from the high frequency power source 220 when power is supplied from the high frequency power source 220 to the power transmission unit 230.

  In FIG. 16, the foreign matter detection sensors 260A and 260B are electrically connected to the power line between the matching unit 240 and the power transmission unit 230 via the rectifying unit 270. The foreign object detection sensors 260 </ b> A and 260 </ b> B may be electrically connected to a power line between the power supply 240 and the power line 240.

  As described above, in the fifth embodiment, foreign matter detection sensors 260A and 260B operate by receiving power output from high-frequency power source 220 during power transmission from power transmission device 200B to vehicle 100D. Thereby, during non-power transmission from power transmission device 200B to vehicle 100D, power is not supplied to foreign matter detection sensors 260A and 260B, and foreign matter detection sensors 260A and 260B are stopped. Therefore, according to the fifth embodiment, the power consumption of foreign matter detection sensors 260A and 260B can be suppressed to the necessary minimum while reliably performing the foreign matter detection between power transmission device 200B and vehicle 100D.

  In each of the above-described embodiments, the power transmission unit 230 is made to resonate with the power transmission unit 230 of the power transmission device 200 (200A, 200B) and the power reception unit 110 of the vehicle 100 (100A to 100D) by an electromagnetic field. However, power may be transmitted from the power transmitting unit 230 to the power receiving unit 110 in a contactless manner by electromagnetic induction. When electric power is transmitted between the power transmission unit 230 and the power reception unit 110 by electromagnetic induction, the coupling coefficient κ between the power transmission unit 230 and the power reception unit 110 is a value close to 1.0.

  Moreover, although each said embodiment demonstrated the case where the power receiving apparatus received non-contactedly from the power transmission apparatus 200 (200A, 200B) was the vehicle 100 (100A-100D), the application range of this invention is not necessarily limited. The power receiving device is not limited to a vehicle, and can be applied to a power receiving device other than the vehicle.

  In the above description, foreign matter detection sensors 150A to 150F, 260A, and 260B correspond to an example of “detection device” in the present invention, and power receiving unit 180 is an example of “another power receiving unit” in the present invention. Corresponds to the example.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  100, 100A to 100D Vehicle, 110, 180 Power receiving unit, 120, 182, 270 Rectifying unit, 130 Power storage device, 140 Power generation unit, 150A to 150F, 260A, 260B Foreign object detection sensor, 160 Vehicle ECU, 170, 250 Communication unit , 184 detection unit, 200, 200A, 200B power transmission device, 210 system power supply, 220 high frequency power supply, 230 power transmission unit, 240 power supply ECU, 162 communication control unit, 164 charge control unit, 166 sensor control unit, 310, 315 variable capacitor, 320, 330, 340 Coil, 335, 350 Capacitor, PL Power line.

Claims (15)

A power receiving device that receives power transmitted from a power transmitting device in a contactless manner,
A power receiving unit for receiving power transmitted from the power transmission device in a contactless manner;
A detection device for detecting a foreign object between the power transmission device and the power reception device;
The detection device is activated in response to the start of power reception by the power reception unit, and is stopped in conjunction with the end of the power reception. A communication unit that communicates with the power transmission device;
The power reception device according to claim 1, wherein the detection device is activated when communication with the power transmission device is established by the communication unit.   The power reception device according to claim 2, wherein the detection device stops when communication with the power transmission device by the communication unit is interrupted.   The power receiving device according to claim 1, wherein the detection device is activated by receiving power received by the power receiving unit.   The power reception device according to claim 4, wherein the detection device is electrically connected to a power line from which the power received by the power reception unit is output, and operates by receiving power from the power line. The detection device includes another power receiving unit that receives power transmitted from the power transmission device in a contactless manner,
The power reception device according to claim 1, wherein the detection device is operated by electric power received by the other power reception unit.   The power receiving device according to claim 1, wherein the detection device detects intrusion of a foreign substance based on presence or absence of a change in detection information with time. The power receiving device is mounted on a vehicle,
The power reception device according to claim 1, wherein the detection device is installed on a lower surface of a vehicle body, and a detection range is set toward a ground facing the power reception unit.   The power receiving device according to claim 1, wherein the detection device is an ultrasonic sensor.   The power receiving device according to claim 1, wherein a difference between the natural frequency of the power receiving unit and the natural frequency of the power transmitting unit of the power transmitting device is ± 10% or less of the natural frequency of the power receiving unit or the natural frequency of the power transmitting unit. .   The power receiving device according to claim 1, wherein a coupling coefficient between the power receiving unit and the power transmitting unit of the power transmitting device is 0.3 or less. The power reception unit is connected to the power transmission unit through at least one of a magnetic field formed between the power reception unit and the power transmission unit of the power transmission device and an electric field formed between the power reception unit and the power transmission unit. Receiving power,
The power receiving device according to claim 1, wherein the magnetic field and the electric field are formed between the power receiving unit and the power transmitting unit and vibrate at a specific frequency. A power receiving device according to claim 1;
A power storage device for storing the power received by the power receiving device;
A vehicle comprising: an electric motor that generates a driving force for driving using electric power stored in the power storage device. A power transmission device that sends power to a power receiving device in a contactless manner,
A power transmission unit that sends power to the power receiving device in a contactless manner;
A detection device for detecting a foreign object between the power transmission device and the power reception device;
The detection device is activated in response to the start of power transmission by the power transmission unit, and stopped in conjunction with the end of the power transmission. A power transmission system for transmitting power from a power transmission device to a power reception device in a contactless manner,
A power transmission unit that sends power from the power transmission device to the power reception device in a contactless manner;
A power receiving unit for receiving power transmitted from the power transmission device in a contactless manner;
A detection device for detecting a foreign object between the power transmission device and the power reception device;
The detection device is activated in response to the start of power transmission from the power transmission device to the power reception device, and is deactivated in conjunction with the stop of the power transmission.

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