WO2015075514A1

WO2015075514A1 - Contactless power transfer system, charging station, and vehicle

Info

Publication number: WO2015075514A1
Application number: PCT/IB2014/002234
Authority: WO
Inventors: Shinji Ichikawa
Original assignee: Toyota Jidosha Kabushiki Kaisha
Priority date: 2013-11-20
Filing date: 2014-10-28
Publication date: 2015-05-28
Also published as: JP2015100246A

Abstract

A contactless power transfer system, a charging station and a vehicle are provided. The contactless power transfer system includes a charging station and a vehicle. A power supply ECU (electronic control unit) (800) provided in the charging station is configured to determine in accordance with a determination criterion whether transfer of electric power from a power transmitting device (20A, 20B, 20C) to a power receiving device (120) is appropriate. The determination criterion is determined based on a characteristic relating to a permissible power transmitting range of a primary coil included in the power transmitting device (20A, 20B, 20C) and a characteristic relating to a permissible power receiving range of a secondary coil included in the power receiving device (120).

Description

CONTACTLESS POWER TRANSFER SYSTEM,

CHARGING STATION, AND VEHICLE

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The invention relates to a contactless power transfer system, a charging station, and a vehicle.

2. Description of Related Art

[0002] Japanese Patent Application Publication No. 2012-161145 (JP

2012-161145 A) describes a technique for carrying out communication between a power transmitting device that wirelessly supplies electric power and a power receiving device mounted on an electric power-driven mobile unit, determining whether electric power is allowed to be wirelessly supplied to the mobile unit based on information acquired through communication, and supplying electric power when it is allowed. The information to be acquired includes information about a location at which a coil is installed in a parking space, a movable range of the coil, a system of the coil, a resonant frequency, and the like, or information about the specifications of a component, and the like.

[0003] Incidentally, the power transmitting device is able to keep a certain power transfer efficiency even when the power receiving device deviates in position within a permissible power transmitting range from an optimal position (position at which the power transfer efficiency that is the ratio of a transmitted electric power to a received electric power is maximum). The permissible power transmitting range is a unique value that is determined based on the characteristic of the power transmitting device. The power receiving device is able to keep a certain power transfer efficiency even when the power transmitting device deviates in position within a permissible power receiving range from an optimal position. The permissible power receiving range is a unique value that is determined based on the characteristic of the power receiving device.

[0004] It is generally difficult to park a vehicle at a position at which the transfer efficiency of electric power from the power transmitting device to the power receiving device is maximum. When the vehicle is parked at a position that deviates from the position at which the transfer efficiency is maximum, unless a combination of the permissible power receiving range of the power receiving device with the permissible power transmitting range of the power transmitting device is compatible, electric power is transferred from the power transmitting device to the power receiving device at an extremely low power transfer efficiency.

[0005] However, the diameter of the coil described in JP 2012-161 145 A does not define a pennissible offset. SUMMARY OF THE INVENTION

[0006] The invention provides a contactless power transfer system, a charging station and a vehicle that are able to prevent transfer of electric power from a power transmitting deice to a power receiving device at an extremely low power transfer efficiency when a combination of a pennissible power receiving range of the power receiving device with a permissible power transmitting range of the power transmitting device is not compatible.

[0007] An aspect of the invention provides a contactless power transfer system. The contactless power transfer system includes a vehicle and a charging station. The vehicle includes a power receiving device and a transmitting unit. The power receiving device includes a secondary coil, and the power receiving device is configured to contactlessly receive electric power. The transmitting unit is configured to transmit information indicating a characteristic relating to a pennissible power receiving range of the secondary coil. The charging station includes a power transmitting device, a receiving unit and a first electronic control unit. The power transmitting device includes a primary coil, and the power transmitting device is configured to contactlessly transfer electric power to the vehicle. The receiving unit is configured to receive the infomiation indicating the characteristic relating to the pennissible power receiving range of the secondary coil. The first electronic control unit is configured to determine in accordance with a detennination criterion whether transfer of electric power from the power transmitting device to the power receiving device is appropriate. The determination criterion is detemiined based on a characteristic relating to a pennissible power transmitting range of the primary coil and the characteristic relating to the pennissible power receiving range of the secondary coil. A power transfer efficiency is higher than or equal to a predetermined value within the permissible power transmitting range of the primary coil, and the power transfer efficiency is higher than or equal to the predetermined value within the permissible power receiving range of the secondary coil.

[0008] With the above-described contactless power transfer system, it is determined at the charging station side whether a combination of the pennissible power transmitting range of the primary coil with the permissible power receiving range of the secondary coil is compatible. Therefore, it is possible to prevent transfer of electric power from the power transmitting device to the power receiving device in a state where the power transfer efficiency is extremely low.

[0009] Another aspect of the invention provides a contactless power transfer system. The contactless power transfer system includes a vehicle and a charging station. The vehicle includes a power receiving device and a receiving unit. The power receiving device includes a secondary coil, and the power receiving device is configured to contactlessly receive electric power. The receiving unit is configured to receive information indicating a characteristic relating to a permissible power transmitting range of a primary coil. The charging station includes a power transmitting device, a transmitting unit and a first electronic control unit. The power transmitting device includes the primary coil, and the power transmitting device is configured to contactlessly transfer electric power to the vehicle. The transmitting unit is configured to transmit the information indicating the characteristic relating to the permissible power transmitting range of the primary coil. The first electronic control unit is configured to determine in accordance with a determination criterion whether transfer of electric power from the power transmitting device to the power receiving device is appropriate. The determination criterion is determined based on the characteristic relating to the permissible power transmitting range of the primary coil and a characteristic relating to a permissible power receiving range of the secondary coil. A power transfer efficiency is higher than or equal to a predetermined value within the permissible power transmitting range of the primary coil, and the power transfer efficiency is higher than or equal to the predetermined value within the permissible power receiving range of the secondary coil.

[0010] With the above-described contactless power transfer system, it is determined at the vehicle side whether a combination of the permissible power transmitting range of the primary coil with the permissible power receiving range of the secondary coil is compatible. Therefore, it is possible to prevent transfer of electric power from the power transmitting device to the power receiving device in a state where the power transfer efficiency is extremely low.

[0011] In the contactless power transfer system, the characteristic relating to the permissible power transmitting range of the primary coil may be a core size of the primary coil, and the characteristic relating to the permissible power receiving range of the secondary coil may be a core size of the secondary coil.

[0012] With the above-described contactless power transfer system, it is possible to determine based on the core size of the primary coil and the core size of the secondary coil whether transfer of electric power is appropriate. [0013] In the contactless power transfer system, the characteristic relating to the permissible power transmitting range of the primary coil may be at least one of a permissible gap length of the primary coil, a pennissible deviation of the secondary coil in a longitudinal direction of the vehicle and a permissible deviation of the secondary coil in a lateral direction of the vehicle. The characteristic relating to the pennissible power receiving range of the secondary coil may be at least one of a pennissible gap length of the secondary coil, a pennissible deviation of the primary coil in the longitudinal direction of the vehicle and a pennissible deviation of the primary coil in the lateral direction of the vehicle.

[0014] With the above-described contactless power transfer system, it is possible to detennine based on at least one of the pennissible gap length of the primary coil, the pennissible deviation of the secondary coil in the longitudinal direction of the vehicle and the permissible deviation of the secondary coil in the lateral direction of the vehicle and at least one of the pennissible gap length of the secondary coil, the permissible deviation of the primary coil in the longitudinal direction of the vehicle and the pennissible deviation of the primary coil in the lateral direction of the vehicle whether transfer of electric power is appropriate.

[0015] In the contactless power transfer system, the vehicle may include a second electronic control unit, the second electronic control unit may be configured to, when position alignment between the power transmitting device and the power receiving device is carried out, detennine whether a voltage received by the power receiving device exceeds a threshold. The second electronic control unit may be configured to complete the position alignment when the received voltage exceeds the threshold. The second electronic control unit may be configured to set the threshold based on a smaller one of a pennissible deviation of the primary coil in a horizontal direction and a pennissible deviation of the secondary coil in the horizontal direction.

[0016] With the above-described contactless power transfer system, a combination of the permissible deviation of the secondary coil in the horizontal direction with the pennissible deviation of the primary coil in the horizontal direction, which has been used at the time of position alignment in order to determine whether transfer of electric power is appropriate, is allowed to be used, so position alignment is appropriately carried out.

[0017] The charging station may include a plurality of the power transmitting devices. Each of the first electronic control unit of the charging station and the second electronic control unit of the vehicle may be configured to, after completion of position alignment between any one of the plurality of power transmitting devices and the power receiving device, execute pairing process for identifying which one of the plurality of power transmitting devices has been subjected to the position alignment.

[0018] With the above-described contactless power transfer system, the charging station is able to determine by which one of the power transmitting devices full-scale electric power should be transmitted.

[0019) The second electronic control unit of the vehicle may be configured to, after completion of the pairing process, determine whether a voltage received by the power receiving device exceeds a threshold. The second electronic control unit may be configured to start receiving full-scale electric power when the received voltage exceeds the threshold. The second electronic control unit may be configured to set the threshold based on a smaller one of a permissible deviation of the primary coil in a horizontal direction and a permissible deviation of the secondary coil in the horizontal direction.

[0020] After the pairing process, before full-scale electric power is transmitted, even when it is detected whether position alignment becomes invalid (a positional deviation is detected) because of movement of the vehicle, a combination of the permissible deviation of the primary coil in the horizontal direction with the pemiissible deviation of the secondary coil in the horizontal direction is used. Thus, with the above-described contactless power transfer system, a positional deviation is appropriately detected.

[0021] Another aspect of the invention provides a charging station. The charging station includes a power transmitting device, a receiving unit and a first electronic control unit. The power transmitting device includes a primary coil, and the power transmitting device is configured to contactlessly transfer electric power to a power receiving device of a vehicle. The receiving unit is configured to receive information indicating a characteristic relating to a pemiissible power receiving range of a secondary coil included in the power receiving device. The first electronic control unit is configured to detemiine in accordance with a determination criterion whether transfer of electric power from the power transmitting device to the power receiving device is appropriate. The determination criterion is detemiined based on a characteristic relating to a permissible power transmitting range of the primary coil and the characteristic relating to the permissible power receiving range of the secondary coil. A power transfer efficiency is higher than or equal to a predetermined value within the permissible power transmitting range of the primary coil, and the power transfer efficiency is higher than or equal to the predetermined value within the permissible power receiving range of the secondary coil. With the above-described charging station, it is possible to determine at the charging station side whether transfer of electric power is appropriate.

[0022] Further another aspect of the invention provides a vehicle. The vehicle includes a power receiving device, a receiving unit and a second electronic control unit. The power receiving device includes a secondary coil, and is configured to contactlessly receive electric power from a power transmitting device provided in a charging station. The receiving unit is configured to receive information indicating a characteristic relating to a permissible power transmitting range of a primary coil included in the power transmitting device. The second electronic control unit is configured to determine in accordance with a determination criterion whether transfer of electric power from the power transmitting device to the power receiving device is appropriate. The determination criterion is determined based on the characteristic relating to the permissible power transmitting range of the primary coil and a characteristic relating to a permissible power receiving range of the secondary coil. In contactless power transfer between the charging station and the vehicle, a power transfer efficiency is higher than or equal to a predetermined value within the permissible power transmitting range of the primary coil, and the power transfer efficiency is higher than or equal to the predetermined value within the permissible power receiving range of the secondary coil. With the above-described vehicle, it is possible to determine at the vehicle side whether transfer of electric power is appropriate.

[0023] With the above-described contactless power transfer system, charging station and vehicle according to the invention, when a combination of a permissible offset of the power receiving device with a permissible offset of the power transmitting device is not compatible, it is possible to prevent transfer of electric power from the power transmitting device to the power receiving device in a state where the power transfer efficiency is extremely low.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIG. 1 is an overall configuration view of a contactless power transfer system that is an example of an embodiment of the invention;

FIG. 2 is a view for illustrating a manner in which a vehicle parks at a parking position within a charging station according to the embodiment of the invention; FIG. 3 is a view showing a state after completion of position alignment between a power transmitting unit and a power receiving unit according to the embodiment;

FIG. 4 is a view for illustrating a path of passage of magnetic fluxes between the power transmitting unit and the power receiving unit according to the embodiment;

FIG. 5 is a view for illustrating an offset according to the embodiment;

FIG. 6 is a view for illustrating an offset according to the embodiment;

FIG. 7 is a flowchart for illustrating the outline of a process that the vehicle and the charging station execute at the time when electric power is contactlessly transferred according to a first embodiment of the invention;

FIG. 8 is a timing chart that shows changes in transmitted electric power and received voltage that change in course of the process of FIG. 7;

FIG. 9 is a table for illustrating a core size class according to the first embodiment;

FIG. 10 is a table that shows a power transfer compatibility map according to the first embodiment;

FIG. 1 1 is a flowchart that shows the procedure of detennining whether transfer of electric power is appropriate according to the first embodiment;

FIG. 12 is a flowchart that shows the procedure of detennining whether transfer of electric power is appropriate according to a first alternative embodiment to the first embodiment;

FIG. 13 is a table that shows a power transfer compatibility map according to a second alternative embodiment to the first embodiment;

FIG. 14 is a table for illustrating a gap class according to a second embodiment of the invention;

FIG. 15 is a table for illustrating an offset class;

FIG. 16 is a table that shows a power transfer compatibility map based on a gap class according to the second embodiment;

FIG. 17 is a table that shows a power transfer compatibility map based on an offset class according to the second embodiment;

FIG. 18 is a flowchart that shows the procedure of detennining whether transfer of electric power is appropriate according to the second embodiment;

FIG. 19 is a graph for illustrating setting of a threshold of received voltage for detennining whether position alignment is successful according to the second embodiment;

FIG. 20 is a flowchart that shows the procedure of detennining whether transfer of electric power is appropriate according to a first alternative embodiment to the second embodiment; FIG. 21 is a table that shows a power transfer compatibility map based on a gap class according to a second alternative embodiment to the second embodiment;

FIG. 22 is a table that shows a power transfer compatibility map based on an offset class according to the second alternative embodiment to the second embodiment; and

FIG. 23 is a timing chart for illustrating an alternative embodiment of a pairing process according to the embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

[0025] Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings. Like reference numerals denote the same or corresponding portions in the drawings, and the description thereof will not be repeated.

[0026] Initially, a first embodiment will be described. The configuration of a contactless power transfer system according to the first embodiment will be described. FIG. 1 is an overall configuration view of a contactless power transfer system that is an example of the first embodiment of the invention.

[0027] In FIG. 1 , the contactless power transfer system according to the first embodiment includes a vehicle 10 and a charging station 90. A power receiving device 120 is mounted on the vehicle 10, and is configured to be able to contactlessly receive electric power. The charging station 90 includes power transmitting devices 20A, 20B, 20C that transmit electric power to a power receiving unit 100 from the outside of the vehicle.

[0028] Hereinafter, the specific configurations of the vehicle 10 and charging station 90 will be described in more details. The vehicle 10 includes the power receiving device 120, an electrical storage device 300, a power generating device 400, a communication device 510, a secondary coil information storage unit 501 , a vehicle ECU 500, and an information device 520. The power receiving device 120 includes the power receiving unit 100, a filter circuit 150 and a rectifying unit 200.

[0029] The charging station 90 includes an external power supply 900, the power transmitting devices 20A, 20B, 20C, a communication device 810, a power supply ECU 800 and a primary coil information storage unit 801. The power transmitting device 20A includes a power supply unit 600A, a filter circuit 61 OA and a power transmitting unit 700A. The power transmitting device 20B includes a power supply unit 600B, a filter circuit 610B and a power transmitting unit 700B. The power transmitting device 20C includes a power supply unit 600C, a filter circuit 6 IOC and a power transmitting unit 700C. [0030] For example, as shown in FIG. 2, the power transmitting devices 20A, 20B, 20C are respectively provided on or in the grounds at parking positions A, B, C. The power receiving device 120 is arranged at the lower side of a vehicle body. The arrangement portion of the power receiving device 120 is not limited to this configuration. For example, if a charging station is configured such that the power transmitting devices 20A, 20B, 20C are provided above the vehicle 10, the power receiving device 120 may be provided at the upper portion of the vehicle body.

[0031] The power receiving unit 100 includes a secondary coil for contactlessly receiving (alternating-current) electric power that is output from any one of the power transmitting units 700A, 700B, 700C of the power transmitting devices 20A, 20B, 20C. Information about the characteristic of the secondary coil (core size, and the like) is stored in the secondary coil information storage unit 501. The power receiving unit 100 outputs received electric power to the rectifying unit 200. The rectifying unit 200 rectifies alternating-current power received by the power receiving unit 100, and outputs the rectified electric power to the electrical storage device 300. The filter circuit 150 is provided between the power receiving unit 100 and the rectifying unit 200. The filter circuit 150 suppresses harmonic noise that occurs at the time when electric power is received from any one of the power transmitting units 700A, 700B, 700C. The filter circuit 150 is, for example, formed of an LC filter including an inductor and a capacitor.

[0032] The electrical storage device 300 is a rechargeable direct-current power supply, and is formed of, for example, a secondary battery, such as a lithium ion battery and a nickel-metal hydride battery. The voltage of the electrical storage device 300 is, for example, about 200 V. The electrical storage device 300 not only stores electric power that is output from the rectifying unit 200 but also stores electric power that is generated by the power generating device 400. The electrical storage device 300 supplies the stored electric power to the power generating device 400. A large-capacitance capacitor may also be employed as the electrical storage device 300. Although not specifically shown in the drawing, a DC-DC converter that adjusts the output voltage of the rectifying unit 200 may be provided between the rectifying unit 200 and the electrical storage device 300.

[0033] The power generating device 400 generates driving force for propelling the vehicle 10 by using electric power that is stored in the electrical storage device 300. Although not specifically shown in the drawing, the power generating device 400, for example, includes an inverter, a motor, drive wheels, and the like. The inverter receives electric power from the electrical storage device 300. The motor is driven by the inverter. The drive wheels are driven by the motor. The power generating device 400 may include a generator and an engine. The generator is used to charge the electrical storage device 300. The engine is able to drive the generator.

[0034] The vehicle ECU 500 includes a central processing unit (CPU), a storage device, an input/output buffer, and the like (all of which are not shown). The vehicle ECU 500 receives signals input from various sensors or outputs control signals to various devices, and controls the devices in the vehicle 10. As an example, the vehicle ECU 500 executes traveling control over the vehicle 10 and charging control over the electrical storage device 300. These controls are not limited to software processing, and may be processed by exclusive hardware (electronic circuit).

[0035] A relay 210 is provided between the rectifying unit 200 and the electrical storage device 300. The relay 210 is turned on by the vehicle ECU 500 when the electrical storage device 300 is charged from any one of the power transmitting devices 20A, 20B, 20C. A system main relay (SMR) 310 is provided between the electrical storage device 300 and the power generating device 400. The SMR 310 is turned on by the vehicle ECU 500 when start-up of the power generating device 400 is required.

[0036] In addition, a relay 202 is provided between the rectifying unit 200 and the relay 210. A voltage VR between both ends of a resistor 201 connected in series with the relay 202 is detected by a voltage sensor 203, and is transmitted to the vehicle ECU 500.

[0037] When the electrical storage device 300 is charged from any one of the power transmitting devices 20A, 20B, 20C, the vehicle ECU 500 communicates with the communication device 810 of the charging station 90 by using the communication device 510, and exchanges infonnation about start/stop of charging, a power receiving condition of the vehicle 10, and the like, with the power supply ECU 800. That is, the communication device 510 provided in the vehicle 10 functions as not only a transmitting unit but also a receiving unit. The communication device 810 provided in the charging station 90 functions as not only a receiving unit but also a transmitting unit.

[0038] FIG. 2 is a view for illustrating a manner in which the vehicle 10 moves to carry out position alignment between the power receiving device 120 and the power transmitting device 20A. As shown in FIG. 2, by using, for example, an in-vehicle camera (not shown) or a power receiving strength in test power transmission (transmission of faint electric power) by the power transmitting unit 700A, the vehicle 10 or the charging station 90 determines whether the position of the secondary coil in the power receiving device 120 is aligned with the position of the primary coil in the power transmitting device 20A, and a user is informed of the result by the infonnation device 520. The user moves the vehicle 10 based on the infonnation obtained from the information device 520 so that the positional relationship between the power receiving device 120 and the power transmitting device 20A becomes a positional relationship suitable for transmission and reception of electric power. The user does not always need to carry out steering operation or accelerator operation. The vehicle 10 may automatically move to carry out position alignment, and the user may watch the movement through the information device 520.

[0039] In the embodiment of the invention, before such position alignment between the power receiving device 120 and the power transmitting device 20A, it is determined whether transfer of electric power from the power transmitting device 20A to the power receiving device 120 is appropriate. A state where transfer of electric power is appropriate means that transfer of electric power is allowed to be carried out at a power transfer efficiency higher than or equal to a predetermined value.

[0040] Referring back to FIG. 1 , the power supply units 600A, 600B, 600C receive electric power from the external power supply 900, such as a commercial system power supply, and generate alternating-current power having a predetermined transmission frequency.

[0041] The power transmitting units 700A, 700B, 700C each include a primary coil for contactlessly transmitting electric power to the power receiving unit 100. Information (core size, and the like) about the characteristic of the primary coil is stored in the primary coil information storage unit 801. In the present embodiment, the power transmitting units 700A, 700B, 700C are merely arranged at different locations, and have the same characteristic. Thus, the primary coils respectively included in the power transmitting units 700A, 700B, 700C have the same characteristic (core size, and the like). The power transmitting unit 700A receives alternating-current power having the transmission frequency from the power supply unit 600A, and contactlessly transmits electric power to the power receiving unit 100 of the vehicle 10 via an electromagnetic field that is generated around the power transmitting unit 700A. The power transmitting unit 700B receives alternating-current power having the transmission frequency from the power supply unit 600B, and contactlessly transmits electric power to the power receiving unit 100 of the vehicle 10 via an electromagnetic field that is generated around the power transmitting unit 700B. The power transmitting unit 700C receives alternating-current power having the transmission frequency from the power supply unit 600C, and contactlessly transmits electric power to the power receiving unit 100 of the vehicle 10 via an electromagnetic field that is generated around the power transmitting unit 700C.

[0042] The filter circuit 61 OA is provided between the power supply unit 600A and the power transmitting unit 700A, and suppresses harmonic noise that arises from the power supply unit 600A. The filter circuit 61 OB is provided between the power supply unit 600B and the power transmitting unit 700B, and suppresses harmonic noise that arises from the power supply unit 600B. The filter circuit 6 I OC is provided between the power supply unit 600C and the power transmitting unit 700C, and suppresses harmonic noise that arises from the power supply unit 600C. Each of the filter circuits 61 OA, 61 OB, 6 IOC is formed of an LC filter including an inductor and a capacitor.

[0043] The power supply ECU 800 includes a CPU, a storage device, an input/output buffer, and the like (all of which are not shown). The power supply ECU 800 receives signals input from various sensors or outputs control signals to various devices, and controls the devices in the charging station 90. As an example, the power supply ECU 800 executes switching control over the power supply unit 600A so that the power supply unit 600A generates alternating-current power having the transmission frequency, the power supply ECU 800 executes switching control over the power supply unit 600B so that the power supply unit 600B generates alternating-current power having the transmission frequency, or the power supply ECU 800 executes switching control over the power supply unit 600C so that the power supply unit 600C generates alternating-current power having the transmission frequency. These controls are not limited to software processing, and may be processed by exclusive hardware (electronic circuit).

[0044] When electric power is transferred to the vehicle 10, the power supply

ECU 800 communicates with the communication device 510 of the vehicle 10 by using the communication device 810, and exchanges information about start/stop of charging, a power receiving condition of the vehicle 10, and the like, with the vehicle 10.

[0045] Alternating-current power having the predetermined transmission frequency is supplied from the power supply unit 600A to the power transmitting unit 700A via the filter circuit 61 OA, alternating-current power having the predetermined transmission frequency is supplied from the power supply unit 600B to the power transmitting unit 700B via the filter circuit 610B, or alternating-current power having the predetermined transmission frequency is supplied from the power supply unit 600C to the power transmitting unit 700C via the filter circuit 6 I OC. The power transmitting units 700A, 700B, 700C and the power receiving unit 100 of the vehicle 10 each include a coil and a capacitor, and is designed to resonate at the transmission frequency. A Q value indicating the resonant strength of each of the power transmitting units 700A, 700B, 700C and power receiving unit 100 is desirably higher than or equal to 100.

[0046] When alternating- current power is supplied from the power supply unit 600A to the power transmitting unit 700A via the filter circuit 61 OA, energy (electric power) is transferred from the power transmitting unit 700A to the power receiving unit 100 through an electromagnetic field that is formed between the primary coil of the power transmitting unit 700A and the secondary coil of the power receiving unit 100. When alternating-current power is supplied from the power supply unit 600B to the power transmitting unit 700B via the filter circuit 610B, energy (electric power) is transferred from the power transmitting unit 700B to the power receiving unit 100 through an electromagnetic field that is formed between the primary coil of the power transmitting unit 700B and the secondary coil of the power receiving unit 100. When alternating-current power is supplied from the power supply unit 600C to the power transmitting unit 700C via the filter circuit 6 I OC, energy (electric power) is transferred from the power transmitting unit 700C to the power receiving unit 100 through an electromagnetic field that is formed between the primary coil of the power transmitting unit 700C and the secondary coil of the power receiving unit 100. Energy (electric power) transferred to the power receiving unit 100 is supplied to the electrical storage device 300 via the filter circuit 150 and the rectifying unit 200.

[0047] Although not particularly shown in the drawing, in the power transmitting device 20A, an isolation transfonner may be provided between the power transmitting unit 700A and the power supply unit 600A (for example, between the power transmitting unit 700A and the filter circuit 61 OA), in the power transmitting device 20B, an isolation transformer may be provided between the power transmitting unit 700B and the power supply unit 600B (for example, between the power transmitting unit 700B and the filter circuit 610B), and, in the power transmitting device 20C, an isolation transfonner may be provided between the power transmitting unit 700C and the power supply unit 600C (for example, between the power transmitting unit 700C and the filter circuit 6 I OC). In the vehicle 10 as well, an isolation transfonner may be provided between the power receiving unit 100 and the rectifying unit 200 (for example, between the power receiving unit 100 and the filter circuit 150).

[0048] The primary coil included in each of the power transmitting units 700A, 700B, 700C and the secondary coil included in the power receiving unit 100 each are a polarized coil in which magnetic fluxes pass from one end of the coil to the other end of the coil.

[0049] When the vehicle 10 parks at the parking position A, electric power is transferred by the power transmitting unit 700A and the power receiving unit 100 as shown in FIG. 3. [0050] FIG. 3 is a view that shows a state after completion of position alignment between the power transmitting unit 700A and the power receiving unit 100. The power transmitting unit 700A includes the primary coil 13A and a sheet-shaped magnetic material (core) 14A. The primary coil 13A is wound around the magnetic material 14A. The power receiving unit 100 includes the secondary coil 12 and a sheet-shaped magnetic material (core) 16. The secondary coil 12 is wound around the magnetic material 16.

[0051] FIG. 4 is a view for illustrating a path of passage of magnetic fluxes between the power transmitting unit 700A and the power receiving unit 100.

[0052] As shown in FIG. 3 and FIG. 4, magnetic fluxes pass through the center portion (the inside of the magnetic material) of each of the coils 13 A, 12 respectively wound around the magnetic materials 14A, 16. Magnetic fluxes that have passed through the inside of the magnetic material 14A from one end of the primary coil 13A to the other end of the primary coil 13A are directed toward one end of the secondary coil 12, pass through the inside of the magnetic material 16 from one end of the secondary coil 12 to the other end of the secondary coil 12, and return to the one end of the primary coil 13 A.

[0053] The barycenter O l of the magnetic material (core) 14A coincides with the barycenter O l of the primary coil 13 A. The barycenter 02 of the magnetic material (core) 16 coincides with the barycenter 02 of the secondary coil 12. The magnetic material 14A and the magnetic material 16 each are arranged perpendicularly to a vertical direction (Z direction). The longitudinal direction of the vehicle 10 is defined as X direction, and the lateral direction of the vehicle 10 is defined as Y direction. The barycenter Ol of the core 14A of the primary coil 13A is defined as the origin of three-dimensional (X, Y, Z) coordinates.

[0054] A vertical (Z-direction) component of the distance between the barycenter Ol of the core 14A of the primary coil 13A and the barycenter 02 of the core 16 of the secondary coil 12 is called gap length. When the horizontal position (that is, X coordinate and Y coordinate) of the barycenter O l of the core 14A of the primary coil 13A coincides with the horizontal position (that is, X coordinate and Y coordinate) of the barycenter 02 of the core 16 of the secondary coil 12, the distance between the barycenter Ol of the core 14A of the primary coil 13A and the barycenter 02 of the core 16 of the secondary coil 12 becomes the gap length.

[0055] Next, an offset will be described with reference to FIG. 5 and FIG. 6. A Y-direction offset is a Y-direction component of the distance between the barycenter Ol of the core 14A of the primary coil 13A and the barycenter 02 of the core 16 of the secondary coil 12. An X-direction offset is an X-direction component of the distance between the barycenter 01 of the core 14A of the primary coil 13A and the barycenter 02 of the core 16 of the secondary coil 12. Although not shown in the drawing, a Z-direction offset is a deviation from a reference gap length that is determined based on, for example, the size of the core 14A of the primary coil 13A or the size of the core 16 of the secondary coil 12.

[0056] Next, the procedure of contactless power transfer will be described. FIG.

7 is a flowchart for illustrating the outline of a process that the vehicle 10 and the charging station 90 execute at the time when electric power is contactlessly transferred. FIG. 8 is a timing chart that shows changes in transmitted electric power and received voltage that change in course of the process of FIG. 7.

[0057] As shown in FIG. 1 , FIG. 7 and FIG. 8, in step S510, when there is a vacant parking position, the power supply ECU 800 of the charging station 90 broadcasts a signal informing a chargeable situation.

[0058] In step S30 and step S530, the vehicle ECU 500 of the vehicle 10 and the power supply ECU 800 of the charging station 90 exchange information about mutual coils, and determines based on the compatibility between the primary coil of the charging station 90 and the secondary coil of the vehicle 10 whether transfer of electric power from the power transmitting devices 20A, 20B, 20C of the charging station 90 to the power receiving device 120 of the vehicle 10.

[0059] When transfer of electric power is inappropriate, the process ends. When transfer of electric power is appropriate, the vehicle ECU 500 proceeds with the process to step S40.

[0060] In step S40, the vehicle ECU 500 transmits a request to transmit faint electric power for position alignment.

[0061] In step S550, in the charging station 90, the power transmitting devices 20 A, 20B, 20C transmit faint electric power for carrying out position alignment with the power receiving device 120.

[0062] In step S50, the vehicle 10 carries out position alignment by automatically or manually moving the vehicle 10 (see timing tl in FIG. 8). During position alignment, the vehicle ECU 500 brings the relay 202 into conduction, and acquires a received voltage VR The received voltage VR is a voltage applied between both ends of the resistor 201 and is detected by the voltage sensor 203. Because this voltage is lower than that during transmission of full-scale electric power, the vehicle ECU 500 sets the relay 210 to an off state so that the voltage is not influenced by the electrical storage device 300 at the time of detection of the voltage.

[0063] In step S60, when the received voltage VR exceeds a threshold TH, the vehicle ECU 500 causes the information device 520 to inform a user of the fact that position alignment is successful. After that, when the user informs that the parking position is OK by pressing a parking switch in the vehicle 10, the process proceeds to step S70 (see timing t2 in FIG. 8).

[0064] In step S70, the vehicle ECU 500 transmits a request to stop transfer of faint electric power for position alignment. In step S560, the power supply ECU 800 of the charging station 90 receives the request to stop transfer of faint electric power, and ends transfer of faint electric power for position alignment from the power transmitting devices 20A, 20B, 20C (see timing t3 in FIG. 8).

[0065] For constant primary-side voltages (output voltages from the power transmitting devices 20A, 20B, 20C), a secondary-side voltage (received voltage VR) changes in response to the distance between the primary coil of each of the power transmitting devices 20A, 20B, 20C and the secondary coil of the power receiving device 120. Therefore, the relationship between the difference in horizontal position between the barycenter Ol of the core of the primary coil and the barycenter 02 of the core of the secondary coil and the received voltage VR is measured in advance, and the received voltage VR for a permissible value of the horizontal position between the barycenter Ol of the core of the primary coil and the barycenter 02 of the core of the secondary coil is set as the threshold TH.

[0066] In step S80 and step S580, the vehicle ECU 500 and the power supply

ECU 800 execute paring process for identifying which one of the power transmitting devices 20A, 20B, 20C has been subjected to position alignment.

[0067] The power supply ECU 800 varies the on duration of transmitted electric power for each power transmitting device. That is, the power transmitting device 20A sets transmitted electric power in the on state for a time TA, the power transmitting device 20B sets transmitted electric power in the on state for a time TB, and the power transmitting device 20C sets transmitted electric power in the on state for a time TC (see timing t4 in FIG. 8).

[0068] The vehicle ECU 500 informs the power supply ECU 800 of the on duration of received electric power. In the example of FIG. 8, the power receiving device 120 receives transmitted electric power from the power transmitting device 20A. The vehicle ECU 500 informs the power supply ECU 800 that the on duration of received electric power is TA. Thus, the power supply ECU 800 understands that position alignment is carried out with the power transmitting device 20A.

[0069] In step S590, the charging station 90 executes full-scale power transmitting process by the power transmitting device subjected to position alignment (see timing t6 in FIG. 8). In the example of FIG. 8, the power transmitting device 20A executes power transmitting process. In step S90, the vehicle 10 executes full-scale power receiving process by the power receiving device 120, and charges the electrical storage device 300 with received electric power.

[0070] In the embodiment of the invention, based on infonnation about the characteristic of the pennissible power transmitting range of the primary coil and information about the characteristic of the pennissible power receiving range of the secondary coil, it is detennined whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate.

[0071] Within the pennissible power transmitting range of the primary coil, the power transfer efficiency is higher than or equal to a predetermined value El . Within the permissible power receiving range of the secondary coil, the power transfer efficiency is higher than or equal to the predetennined value E l .

[0072] The permissible power transmitting range of the primary coil is defined by a pennissible gap length of the primary coil and a pennissible horizontal deviation of the secondary coil. The pennissible horizontal deviation of the secondary coil is a permissible value of a deviation of the secondary coil from a predetennined position of the secondary coil. The permissible gap length of the primary coil is a pennissible value of the Z-direction distance between the primary coil and the secondary coil.

[0073] The pennissible power receiving range of the secondary coil is defined by a pennissible gap length of the secondary coil and a pennissible horizontal deviation of the primary coil. The pennissible horizontal deviation of the primary coil is a pennissible value of a deviation of the primary coil from a predetennined position of the primary coil. The pennissible gap length of the secondary coil is a permissible value of the Z-direction distance between the secondary coil and the primary coil.

[0074] The inventors of the present application focused on the fact that, as the core size of the primary coil increases, the power transfer efficiency is maintained even when the secondary coil is distanced from the primary coil, and as the core size of the secondary coil increases, the power transfer efficiency is maintained even when the primary coil is distanced from the secondary coil.

[0075] In the first embodiment, information about the core size of the primary coil, which is stored in the primary coil information storage unit 801 , is used as the information about the characteristic of the pennissible power transmitting range of the primary coil, and infonnation about the core size of the secondary coil, which is stored in the secondary coil information storage unit 501 , is used as the information about the characteristic of the pennissible power receiving range of the secondary coil.

[0076] In the first embodiment, the core size class of each of the primary coil and the secondary coil is defined as shown in FIG. 9. That is, the core size class S indicates that the length of the core of the coil in a X direction is 200 mm and the length of the core of the coil in a Y direction is 200 mm. The primary coil of the core size class S has the permissible power transmitting range of +AXS1 , ±AYS 1 , ±AZS1 with respect to the center of the core of the primary coil. The secondary coil of the core size class S has the pennissible power receiving range of ±AXS2, ±AYS2, ±AZS2 with respect to the center of the core of the secondary coil.

[0077] The core size class M indicates that the length of the core of the coil in the

X direction is 300 mm and the length of the core of the coil in the Y direction is 300 mm.

The primary coil of the core size class M has the pennissible power transmitting range of

±ΔΧΜ1 , ±ΔΥΜ1 , ±ΔΖΜ1 with respect to the center of the core of the primary coil. The secondary coil of the core size class M has the pennissible power receiving range of

±ΔΧΜ2, ±ΔΥΜ2, ±ΔΖΜ2 with respect to the center of the core of the secondary coil.

[0078] The core size class L indicates that the length of the core of the coil in the

X direction is 400 mm and the length of the core of the coil in the Y direction is 400 mm.

The primary coil of the core size class L has the pennissible power transmitting range of ±AXL, ±AYL, ±AZL with respect to the center of the core of the primary coil. The secondary coil of the core size class L has the pennissible power receiving range of ±AXL2,

±AYL2, ±AZL2 with respect to the center of the core of the secondary coil. However, the following relationships hold.

AXS l < ΔΧΜ1 < AXL1

AYS l < ΔΥΜ1 < AYLl

AZS l < ΔΖΜ1 < AZLl

AXS2 < ΔΧΜ2 < AXL2

AYS2 < ΔΥΜ2 < AYL2

AZS2 < ΔΖΜ2 < AZL2

[0079] In the first embodiment, in accordance with a power transfer compatibility map shown in FIG. 10, it is detennined whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate.

[0080] The power transfer compatibility map shown in FIG. 10 defines whether transfer of electric power is appropriate for a combination of the core size class of the primary coil with the core size class of the secondary coil. This reflects the results obtained through an experiment by the inventors of the present application. In the experiment, it is determined that transfer of electric power is appropriate when the power transfer efficiency is higher than or equal to a predetermined value A in a state where the barycenter Ol of the core of the primary coil and the barycenter 02 of the core of the secondary coil are distanced by a predetermined value in the X, Y, or Z direction; whereas it is determined that transfer of electric power is inappropriate when the power transfer efficiency is lower than the predetermined value A in a state where the barycenter 01 of the core of the primary coil and the barycenter 02 of the core of the secondary coil are distanced by the predetermined value in the X, Y, or Z direction.

[0081] As shown in FIG. 10, when the core size class of the primary coil is S and the core size class of the secondary coil is L, it is determined that transfer of electric power is inappropriate. This is because electric power is difficult to be transferred from the power-transmitting-side primary coil having a relatively small core size to the power-receiving-side secondary coil having a relatively large core size.

[0082] FIG. 1 1 is a flowchart that shows the procedure of determining whether transfer of electric power is appropriate according to the first embodiment.

[0083] In step S I 01 , the vehicle ECU 500 reads the information indicating the core size class of the secondary coil from the secondary coil information storage unit 501 , and transmits through the communication device 510 the information indicating the core size class of the secondary coil.

[0084] In step S I 02, the power supply ECU 800 receives through the communication device 810 the information indicating the core size class of the secondary coil.

[0085] In step S I 03, the power supply ECU 800 reads the information indicating the core size class of the primary coil from the primary coil information storage unit 801.

[0086] In step S I 04, the power supply ECU 800 determines in accordance with the power transfer compatibility map shown in FIG. 10 whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate. When transfer of electric power is appropriate, the process proceeds to step S I 05; whereas, when transfer of electric power is inappropriate, the process proceeds to step S I 06.

[0087] In step S I 05, the power supply ECU 800 transmits through the communication device 810 the information indicating that transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate. [0088] In step S I 06, the power supply ECU 800 transmits through the communication device 810 the information indicating that transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is inappropriate.

[0089] In step SI 07, the vehicle ECU 500 receives through the communication device 510 the information indicating whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate.

[0090] In step S I 08, the vehicle ECU 500 causes the information device 520 to display the information indicating whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate.

[0091] As described above, in the present embodiment, it is determined based on a combination of the core size classes whether a combination of the permissible power receiving range of the secondary coil included in the power receiving device with the permissible power transmitting range of the primary coil included in the power transmitting device is compatible, and, when the combination is not compatible, transfer of electric power is not carried out.

[0092] In the above-described embodiment, the power supply ECU 800 reads the information indicating the core size class of each primary coil from the primary coil information storage unit 801 , and determines in accordance with the power transfer compatibility map shown in FIG. 10 whether transfer of electric power is appropriate; however, the power supply ECU 800 is not limited to this configuration. Because the core size of each primary coil in the charging station does not change, instead of the power transfer compatibility map that defines whether transfer of electric power is appropriate for a combination of the core size class of each primary coil with the core size class of the secondary coil as shown in FIG. 10, a power transfer compatibility map that defines whether transfer of electric power is appropriate for the core size of the secondary coil may be used. That is, when the core size class of each primary coil of the charging station is S, a power transfer compatibility map that defines that transfer of electric power is appropriate when the core size class of the secondary coil is S, transfer of electric power is appropriate when the core size class of the secondary coil is M and transfer of electric power is inappropriate when the core size class of the secondary coil is L may be used. Thus, the process of reading the core size class of the primary coil in step SI 03 of FIG. 1 1 is not required.

[0093] Next, a first alternative embodiment to the first embodiment will be described. FIG. 12 is a flowchart that shows the procedure of determining whether transfer of electric power is appropriate according to the first alternative embodiment to the first embodiment.

[0094] In step S201 , the power supply ECU 800 reads the information indicating the core size class of the primary coil from the primary coil infonnation storage unit 801 , and transmits through the communication device 810 the infonnation indicating the core size class of the primary coil.

[0095] In step S202, the vehicle ECU 500 receives through the communication device 510 the infonnation indicating the core size class of the primary coil.

[0096] In step S203, the vehicle ECU 500 reads the infonnation indicating the core size class of the secondary coil from the secondary coil infonnation storage unit 501.

[0097] In step S204, the vehicle ECU 500 determines in accordance with the power transfer compatibility map shown in FIG. 10 whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate. When transfer of electric power is appropriate, the process proceeds to step S205; whereas, when transfer of electric power is inappropriate, the process proceeds to step S206.

[0098] In step S205, the vehicle ECU 500 transmits through the communication device 510 the information indicating that transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate.

[0099] In step S206, the vehicle ECU 500 transmits through the communication device 510 the infonnation indicating that transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is inappropriate.

[0100] In step S207, the power supply ECU 800 receives through the communication device 810 the infonnation indicating whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate.

[0101] In step S208, the vehicle ECU 500 causes the infonnation device 520 to display the infonnation indicating whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate.

[0102] Next, a second alternative embodiment to the first embodiment will be described. In the second alternative embodiment to the first embodiment, it is detennined in accordance with a power transfer compatibility map shown in FIG. 13 instead of the power transfer compatibility map shown in FIG. 10 whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate. [0103] In the power transfer compatibility map shown in FIG. 13, in an experiment, it is determined that transfer of electric power is appropriate when the power transfer efficiency is higher than or equal to a predetermined value B higher than the predetennined value A in the first embodiment; whereas it is detennined that transfer of electric power is inappropriate when the power transfer efficiency is lower than the predetennined value B.

[0104] When the power transfer compatibility map shown in FIG. 13 is used, the case where transfer of electric power is inappropriate increases as compared to when the power transfer compatibility map shown in FIG. 10 is used. However, it is possible to prevent transfer of electric power at a low power transfer efficiency.

[0105] Next, a second embodiment of the invention will be described. In the second embodiment, the predetermined position of the primary coil and the predetermined position of the secondary coil are defined as follows.

[0106] The predetermined horizontal position of the primary coil is a position at which the barycenter 01 of the core of the primary coil and the barycenter 02 of the core of the secondary coil coincide with each other in the horizontal direction (that is, a position at which the power transfer efficiency is maximum). The predetennined vertical position of the primary coil is a position at which the gap length that is the vertical component of the distance to the secondary coil is a reference gap length (a gap length at which the power transfer efficiency becomes a predetermined value E2) of the secondary coil, which is determined based on the core size of the secondary coil.

[0107] The predetennined horizontal position of the secondary coil is a position at which the barycenter 01 of the core of the primary coil and the barycenter 02 of the core of the secondary coil coincide with each other in the horizontal direction (that is, a position at which the power transfer efficiency is maximum). The predetennined vertical position of the secondary coil is a position at which the gap length that is the vertical component of the distance to the primary coil is a reference gap length (a gap length at which the power transfer efficiency is the predetermined value E2) of the primary coil, which is determined based on the core size of the primary coil.

[0108] In the second embodiment, as a characteristic relating to the permissible power transmitting range of the primary coil, a permissible gap length of the primary coil, a permissible value of a deviation of the secondary coil in the vehicle longitudinal direction (X direction) (permissible X-direction offset) from the predetennined position of the secondary coil, and a pennissible value of a deviation of the secondary coil in the vehicle lateral direction (Y direction) (permissible Y-direction offset) from the predetennined position of the secondary coil are used.

[0109] The permissible gap length of the primary coil is the sum of the reference gap length of the primary coil and the absolute value of a permissible value of a vertical deviation of the secondary coil (permissible Z-direction offset) from the predetermined position of the secondary coil.

[0110] Within the permissible power transmitting range that is determined based on the above-described permissible value of the X-direction deviation of the secondary coil, permissible value of the Y-direction deviation of the secondary coil and the permissible gap length of the primary coil, the power transfer efficiency is higher than or equal to the predetermined value El . However, the relationship El < E2 holds.

[0111] As the characteristic relating to the permissible power receiving range of the secondary coil, a permissible gap length of the secondary coil, a permissible value of a deviation of the primary coil in the vehicle longitudinal direction (X direction) (permissible X-direction offset) from the predetermined position of the primary coil, and a permissible value of a deviation of the primary coil in the vehicle lateral direction (Y direction) (permissible Y-direction offset) from the predetermined position of the primary coil are used.

[0112] The pennissible gap length of the secondary coil is the sum of the reference gap length of the secondary coil and the absolute value of a permissible value of a vertical deviation of the primary coil (pennissible Z-direction offset) from the predetermined position of the primary coil.

[0113] Within the permissible power receiving range that is determined based on the above-described pennissible value of the X-direction deviation of the primary coil, permissible value of the Y-direction deviation of the primary coil and the permissible gap length of the secondary coil, the power transfer efficiency is higher than or equal to the predetermined value El . However, the relationship El < E2 holds.

[0114] In the following description, a pennissible offset means a combination of an X-direction offset, a Y-direction offset and a Z-direction offset.

[0115] In the second embodiment, it is determined based on the infonnation about the reference gap length and pennissible offset of the primary coil and the information about the reference gap length and permissible offset of the secondary coil whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate. The infonnation about the reference gap length and permissible offset of the primary coil is stored in the primary coil information storage unit 801. The information about the reference gap length and permissible offset of the secondary coil is stored in the secondary coil information storage unit 501.

[0116] In the second embodiment, the gap class of each of the primary coil and the secondary coil is defined as shown in FIG. 14. That is, when the horizontal position of the barycenter 01 of the core of the primary coil coincides with the horizontal position of the barycenter 02 of the core of the secondary coil, the gap class S of the primary coil has the reference gap length of 100 mm, the gap class M of the primary coil has the reference gap length of 150 mm, and the gap class L of the primary coil has the reference gap length of 200 mm.

[0117] When the horizontal position of the barycenter 01 of the core of the primary coil coincides with the horizontal position of the barycenter 02 of the core of the secondary coil, the gap class S of the secondary coil has the reference gap length of 100 mm, the gap class M of the secondary coil has the reference gap length of 150 mm, and the gap class L of the secondary coil has the reference gap length of 200 mm.

[0118] In the second embodiment, the offset class of each of the primary coil and the secondary coil is defined as shown in FIG. 15.

[0119] The offset class S of the primary coil indicates that the permissible value of an X-direction deviation (permissible X-direction offset) from the predetermined position of the secondary coil is ±50 mm, the pennissible value of a Y-direction deviation (pennissible Y-direction offset) from the predetemiined position of the secondary coil is ±50 mm, and the pennissible value of a Z-direction deviation (pennissible Z-direction offset) from the predetermined position of the secondary coil is ±10 mm. The offset class M of the primary coil indicates that the permissible value of an X-direction deviation (pennissible X-direction offset) from the predetermined position of the secondary coil is ±100 mm, the pennissible value of a Y-direction deviation (pennissible Y-direction offset) from the predetemiined position of the secondary coil is ±100 mm, and the pennissible value of a Z-direction deviation (pennissible Z-direction offset) from the predetemiined position of the secondary coil is ±20 mm. The offset class L of the primary coil indicates that the pennissible value of an X-direction deviation (pennissible X-direction offset) from the predetermined position of the secondary coil is ±150 mm, the pennissible value of a Y-direction deviation (pennissible Y-direction offset) from the predetennined position of the secondary coil is ±150 mm, and the pennissible value of a Z-direction deviation (permissible Z-direction offset) from the predetemiined position of the secondary coil is ±40 mm.

[0120] The offset class S of the secondary coil indicates that the permissible value of an X-direction deviation (pennissible X-direction offset) from the predetermined position of the primary coil is ±50 mm, the permissible value of a Y-direction deviation (permissible Y-direction offset) from the predetermined position of the primary coil is ±50 mm, and the permissible value of a Z-direction deviation (permissible Z-direction offset) from the predetermined position of the primary coil is ± 10 mm. The offset class M of the secondary coil indicates that the permissible value of an X-direction deviation (permissible X-direction offset) from the predetermined position of the primary coil is ±100 mm, the permissible value of a Y-direction deviation (permissible Y-direction offset) from the predetermined position of the primary coil is ± 100 mm, and the permissible value of a Z-direction deviation (permissible Z-direction offset) from the predetennined position of the primary coil is ±20 mm. The offset class L of the secondary coil indicates that the pennissible value of an X-direction deviation (pennissible X-direction offset) from the predetennined position of the primary coil is ±150 mm, the pennissible value of a Y-direction deviation (pennissible Y-direction offset) from the predetennined position of the primary coil is ±150 mm, and the pennissible value of a Z-direction deviation (pennissible Z-direction offset) from the predetennined position of the primary coil is ±40 mm.

[0121] In the second embodiment, it is detennined in accordance with a power transfer compatibility map shown in FIG. 16 and a power transfer compatibility map shown in FIG. 17 whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate.

[0122] The power transfer compatibility map shown in FIG. 16 defines whether transfer of electric power is appropriate for a combination of the gap class of the primary coil with the gap class of the secondary coil. This reflects the results obtained through an experiment by the inventors of the present application. In the experiment, it is detennined that transfer of electric power is appropriate when the power transfer efficiency is higher than or equal to the predetennined value A in a state where the barycenter 01 of the core of the primary coil and the barycenter 02 of the core of the secondary coil are distanced by the predetennined value in the X, Y, or Z direction; whereas it is determined that transfer of electric power is inappropriate when the power transfer efficiency is lower than the predetennined value A in a state where the barycenter 01 of the core of the primary coil and the barycenter 02 of the core of the secondary coil are distanced by the predetermined value in the X, Y. or Z direction.

[0123] As shown in FIG. 16, when the gap class of the primary coil is S and the gap class of the secondary coil is L, it is determined that transfer of electric power is inappropriate. This is because, for example, as one factor, a coil having a small reference gap length has a small core size and a coil having a large reference gap length has a large core size and, therefore, it is presumable that electric power is difficult to be transferred from the power-transmitting-side primary coil having a small core size to the power-receiving-side secondary coil having a large core size.

[0124] The power transfer compatibility map shown in FIG. 17 defines whether transfer of electric power is appropriate for a combination of the offset class of the primary coil with the offset class of the secondary coil. This reflects the results obtained through an experiment by the inventors of the present application. In the experiment, it is determined that transfer of electric power is appropriate when the power transfer efficiency is higher than or equal to the predetermined value A in a state where the barycenter 01 of the core of the primary coil and the barycenter 02 of the core of the secondary coil are distanced by the predetermined value in the X, Y, or Z direction; whereas it is determined that transfer of electric power is inappropriate when the power transfer efficiency is lower than the predetermined value A in a state where the barycenter Ol of the core of the primary coil and the barycenter 02 of the core of the secondary coil are distanced by the predetermined value in the X, Y, or Z direction.

[0125] As shown in FIG. 17, when the offset class of the primary coil is S and the offset class of the secondary coil is L, it is determined that transfer of electric power is inappropriate. This is because, for example, as one factor, a coil having a small permissible offset has a small core size and a coil having a large permissible offset has a large core size and, therefore, electric power is difficult to be transferred from the power-transmitting-side primary coil having a small core size to the power-receiving-side secondary coil having a large core size.

[0126] FIG. 18 is a flowchart that shows the procedure of determining whether transfer of electric power is appropriate according to the second embodiment.

[0127] In step S301 , the vehicle ECU 500 reads the information indicating the gap class and offset class of the secondary coil from the secondary coil information storage unit 501 , and transmits through the communication device 510 the information indicating the gap class and offset class of the secondary coil.

[0128] In step S302, the power supply ECU 800 receives through the communication device 810 the information indicating the gap class and offset class of the secondary coil.

[0129] In step S303, the power supply ECU 800 reads the information indicating the gap class and offset class of the primary coil from the primary coil information storage unit 801. [0130] In step S304, the power supply ECU 800 detemiines in accordance with the power transfer compatibility map shown in FIG. 16 and the power transfer compatibility map shown in FIG. 17 whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate. That is, the power supply ECU 800 determines that transfer of electric power is appropriate when transfer of electric power is appropriate for the gap class in the power transfer compatibility map shown in FIG. 16 and transfer of electric power is appropriate for the offset class in the power transfer compatibility map shown in FIG. 17. The power supply ECU 800 detemiines that transfer of electric power is inappropriate when transfer of electric power is inappropriate for the gap class in the power transfer compatibility map shown in FIG. 16 or when transfer of electric power is inappropriate for the offset class in the power transfer compatibility map shown in FIG. 17. When transfer of electric power is appropriate, the process proceeds to step S305; whereas, when transfer of electric power is inappropriate, the process proceeds to step S306.

[0131] In step S305, the power supply ECU 800 transmits through the communication device 810 the information indicating that transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate and the information about the gap class, offset class and core size class of the primary coil.

[0132] In step S306, the power supply ECU 800 transmits through the communication device 810 the information indicating that transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is inappropriate.

[0133] In step S307, the vehicle ECU 500 receives through the communication device 510 the information indicating whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate. When transfer of electric power is appropriate, the vehicle ECU 500 further receives the information about the gap class, offset class and core size class of the primary coil.

[0134] In step S308, the vehicle ECU 500 causes the information device 520 to display the information indicating whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate.

[0135] In position alignment of any one of the power transmitting devices 20A, 20B, 20C with the power receiving device 120 in step S50 and step S550 in FIG. 7, the voltage received by the power receiving device 120 is measured by the voltage sensor 203, the vehicle ECU 500 determines whether the measured voltage VR exceeds the threshold TH, and the vehicle ECU 500 completes position alignment when the measured voltage VR exceeds the threshold TH (position alignment is OK).

[0136] In the second embodiment, the vehicle ECU 500 sets the threshold TH based on a smaller one of the pennissible horizontal offset of the primary coil and the pennissible horizontal offset of the secondary coil.

[0137] FIG. 19 is a graph for illustrating setting of the threshold TH of the received voltage for determining whether position alignment is successful.

[0138] A curve PX shown in FIG. 19 is a graph that shows a received voltage to a horizontal deviation between the barycenter 01 o the core of the primary coil and the barycenter 02 of the core of the secondary coil.

[0139] The curve PX is determined based on at least one of the gap class, offset class and core size class of the primary coil and at least one of the gap class, offset class and core size class of the secondary coil.

[0140] Thus, the vehicle ECU 500 detennines the curve PX based on at least one of the gap class, offset class and core size class of the primary coil and at least one of the gap class, offset class and core size class of the secondary coil. The vehicle ECU 500 selects a smaller one of the offset class of the primary coil and the offset class of the secondary coil. For example, when the offset class of the primary coil is S and the offset class of the secondary coil is M, the vehicle ECU 500 selects the smaller offset class S. The vehicle ECU 500 calculates the root-sum-square value of the pennissible X-direction offset of the selected offset class and the permissible Y-direction offset of the selected offset class as a pennissible deviation. For example, when the selected offset class is S, the square root of (50^' + 50') is calculated as a pennissible deviation. The vehicle ECU 500 sets the threshold TH to the received voltage at the time when a deviation in the detennined curve PX is a pennissible deviation.

[0141] After step S80 in FIG. 7, before step S90, the process of detecting a positional deviation between the intended one of the power transmitting devices 20A, 20B, 20C and the power receiving device 120 may be executed. Position alignment is successful, the vehicle 10 is parked, and then the parking position of the vehicle 10 is displaced as a result of, for example, loading or unloading of baggage to or from the vehicle 10, position alignment between the primary coil and the secondary coil in step S50 and step S550 becomes invalid, so the power receiving process in step S90 should not be executed.

[0142] In detecting a positional deviation, as in the case of position alignment, in the charging station 90, the power transmitting devices 20A, 20B, 20C transmit faint electric power for position alignment with the power receiving device 120. The voltage received by the power receiving device 120 is measured by the voltage sensor 203, the vehicle ECU 500 determines whether the measured voltage VR exceeds the threshold TH, confirms that the aligned position is not displaced when the measured voltage VR exceeds the threshold TH, and proceeds with the process to step S90. As in the case of position alignment, at the time of detecting a positional deviation as well, the vehicle ECU 500 sets the threshold TH based on a smaller one of the permissible offset of the primary coil and the permissible offset of the secondary coil. The threshold is the same as the threshold TH for position alignment, so the description thereof will not be repeated.

[0143] When it is confirmed that position alignment is successful, the vehicle

ECU 500 informs the power supply ECU 800 that position alignment is successful. After that, the power supply ECU 800 starts transmitting full-scale electric power, and the vehicle ECU 500 starts receiving full-scale electric power.

[0144] As described above, in the present embodiment, it is determined based on a combination of the offset classes and a combination of the gap classes whether a combination of the permissible power receiving range of the secondary coil included in the power receiving device with the pennissible power transmitting range of the primary coil included in the power transmitting device is compatible, and, when the combination is not compatible, transfer of electric power is not carried out.

[0145] In the present embodiment, whether transfer of electric power is appropriate is determined by using both the gap class and the offset class; however, determination as to whether transfer of electric power is appropriate is not limited to this configuration. In detennining whether transfer of electric power is appropriate, when the gap class is a main factor, whether transfer of electric power is appropriate may be determined by using only the gap class.

[0146] In this case, in step S301 to step S303 in FIG. 18, only the information about the gap class of the secondary coil just needs to be transferred between the vehicle 10 and the charging station 90, and, in the charging station 90, only the infonnation about the gap class of the primary coil just needs to be read from the primary coil infonnation storage unit. In step S304, whether transfer of electric power is appropriate just needs to be determined only by using the power transfer compatibility map shown in FIG. 16.

[0147] In the present embodiment, the permissible X-direction offset, the permissible Y-direction offset and the pennissible Z-direction offset are determined by the offset class; however, the offset class is not limited to detennining these pennissible offsets. At least one of these three pennissible offsets may be determined by the offset class. [0148] Next, a first alternative embodiment to the second embodiment will be described. FIG. 20 is a flowchart that shows the procedure of detemiining whether transfer of electric power is appropriate according to the first alternative embodiment to the second embodiment.

[0149] In step S401 , the power supply ECU 800 reads the information indicating the gap class and offset class of the primary coil from the primary coil information storage unit 801 , and transmits through the communication device 810 the infonnation indicating the gap class and offset class of the primary coil.

[0150] In step S402, the vehicle ECU 500 receives through the communication device 510 the infonnation indicating the gap class and offset class of the primary coil.

[0151] In step S403, the vehicle ECU 500 reads the information indicating the gap class and offset class of the secondary coil from the secondary coil infonnation storage unit 501.

[0152] In step S404, the vehicle ECU 500 detennines in accordance with the power transfer compatibility map shown in FIG. 16 and the power transfer compatibility map shown in FIG. 17 whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate. That is, the vehicle ECU 500 detennines that transfer of electric power is appropriate when transfer of electric power is appropriate for the gap class in the power transfer compatibility map shown in FIG. 16 and transfer of electric power is appropriate for the offset class in the power transfer compatibility map shown in FIG. 17. The vehicle ECU 500 determines that transfer of electric power is inappropriate when transfer of electric power is inappropriate for the gap class in the power transfer compatibility map shown in FIG. 16 or when transfer of electric power is inappropriate for the offset class in the power transfer compatibility map shown in FIG. 17. When transfer of electric power is appropriate, the process proceeds to step S405; whereas, when transfer of electric power is inappropriate, the process proceeds to step S406.

[0153] In step S405, the vehicle ECU 500 transmits through the communication device 510 the infonnation indicating that transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate.

[0154] In step S406, the vehicle ECU 500 transmits through the communication device 510 the information indicating that transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is inappropriate.

[0155] In step S407, the power supply ECU 800 receives through the communication device 810 the information indicating whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate.

[0156] In step S408, the vehicle ECU 500 causes the infonnation device 520 to display the infonnation indicating whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate.

[0157] Next, a second alternative embodiment to the second embodiment will be described. In the second alternative embodiment to the second embodiment, it is detennined in accordance with a power transfer compatibility map shown in FIG. 21 instead of the power transfer compatibility map shown in FIG. 16 whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate.

[0158] In the power transfer compatibility map shown in FIG. 21 , in an experiment, it is detennined that transfer of electric power is appropriate when the power transfer efficiency is higher than or equal to the predetennined value B higher than the predetennined value A in the second embodiment; whereas it is detennined that transfer of electric power is inappropriate when the power transfer efficiency is lower than the predetennined value B.

[0159] In the second alternative embodiment to the second embodiment, it is detennined in accordance with a power transfer compatibility map shown in FIG. 22 instead of the power transfer compatibility map shown in FIG. 17 whether transfer of electric power from the power transmitting devices 20A, 20B, 20C to the power receiving device 120 is appropriate.

[0160] In the power transfer compatibility map shown in FIG. 22, in an experiment, it is determined that transfer of electric power is appropriate when the power transfer efficiency is higher than or equal to the predetennined value B higher than the predetermined value A in the second embodiment; whereas it is detennined that transfer of electric power is inappropriate when the power transfer efficiency is lower than the predetennined value B.

[0161] When the power transfer compatibility maps shown in FIG. 21 and FIG. 22 are used, the case where transfer of electric power is inappropriate increases as compared to when the power transfer compatibility maps shown in FIG. 16 and FIG. 17 are used. However, it is possible to prevent transfer of electric power at a low power transfer efficiency.

[0162] The invention is not limited to the above-described first and second embodiments, and also encompasses, for example, the following alternative embodiments. [0163] FIG. 23 is a timing chart for illustrating an alternative embodiment of the pairing process. In FIG. 23, the power supply ECU 800 varies the on/off switching period of transmitted electric power for each power transmitting device. That is, the power transmitting device 20A switches between on/off states of transmitted electric power in each period ΔΤΑ, the power transmitting device 20B switches between on/off states of transmitted electric power in each period ΔΤΒ, and the power transmitting device 20C switches between on/off states of transmitted electric power in each period ATC (see timing t4 in FIG. 23).

[0164] The vehicle ECU 500 informs the on/off switching period of received electric power to the power supply ECU 800. h the example of FIG. 23, the power receiving device 120 receives transmitted electric power from the power transmitting device 20A. The vehicle ECU 500 informs the power supply ECU 800 that the on/off switching period of received electric power is ΔΤΑ. Thus, the power supply ECU 800 understands that position alignment is carried out with the power transmitting device 20A (see timing t5 in FIG. 23).

Claims

CLAIMS:

1. A contactless power transfer system comprising:

a vehicle including a power receiving device and a transmitting unit, the power receiving device including a secondary coil, the power receiving device being configured to contactlessly receive electric power, and the transmitting unit being configured to transmit infonnation indicating a characteristic relating to a pennissible power receiving range of the secondary coil; and

a charging station including a power transmitting device, a receiving unit and a first electronic control unit, the power transmitting device including a primary coil, the power transmitting device being configured to contactlessly transfer electric power to the vehicle, the receiving unit being configured to receive the infonnation indicating the characteristic relating to the pennissible power receiving range of the secondary coil, the first electronic control unit being configured to detennine in accordance with a determination criterion whether transfer of electric power from the power transmitting device to the power receiving device is appropriate, the detennination criterion being determined based on a characteristic relating to a pennissible power transmitting range of the primary coil and the characteristic relating to the pennissible power receiving range of the secondary coil, a power transfer efficiency being higher than or equal to a predetermined value within the pennissible power transmitting range of the primary coil, and the power transfer efficiency being higher than or equal to the predetennined value within the pennissible power receiving range of the secondary coil.

2. A contactless power transfer system comprising:

a vehicle including a power receiving device and a receiving unit, the power receiving device including a secondary coil, the power receiving device being configured to contactlessly receive electric power, and the receiving unit being configured to receive infonnation indicating a characteristic relating to a pennissible power transmitting range of a primary coil; and

a charging station including a power transmitting device, a transmitting unit and a first electronic control unit, the power transmitting device including a primary coil, the power transmitting device being configured to contactlessly transfer electric power to the vehicle, the transmitting unit being configured to transmit the infonnation indicating the characteristic relating to the pennissible power transmitting range of the primary coil, the first electronic control unit being configured to detennine in accordance with a determination criterion whether transfer of electric power from the power transmitting device to the power receiving device is appropriate, the determination criterion being determined based on the characteristic relating to the permissible power transmitting range of the primary coil and a characteristic relating to a permissible power receiving range of the secondary coil, a power transfer efficiency being higher than or equal to a predetermined value within the pennissible power transmitting range of the primary coil, and the power transfer efficiency being higher than or equal to the predetermined value within the pennissible power receiving range of the secondary coil.

3. The contactless power transfer system according to claim 1 or 2, wherein the characteristic relating to the pennissible power transmitting range of the primary coil is a core size of the primary coil, and the characteristic relating to the pennissible power receiving range of the secondary coil is a core size of the secondary coil.

4. The contactless power transfer system according to claim 1 or 2, wherein the characteristic relating to the permissible power transmitting range of the primary coil is at least one of a pennissible gap length of the primary coil, a pennissible deviation of the secondary coil in a vehicle longitudinal direction and a pennissible deviation of the secondary coil in a vehicle lateral direction, and

the characteristic relating to the permissible power receiving range of the secondary coil is at least one of a pennissible gap length of the secondary coil, a pennissible deviation of the primary coil in the vehicle longitudinal direction and a pennissible deviation of the primary coil in the vehicle lateral direction.

5. The contactless power transfer system according to claim 4, wherein

the vehicle includes a second electronic control unit, the second electronic control unit is configured to, when position alignment between the power transmitting device and the power receiving device is carried out, determine whether a voltage received by the power receiving device exceeds a threshold, the second electronic control unit is configured to complete the position alignment when the received voltage exceeds the threshold, and the second electronic control unit is configured to set the threshold based on a smaller one of a pennissible deviation of the primary coil in a horizontal direction and a permissible deviation of the secondary coil in the horizontal direction.

6. The contactless power transfer system according to claim 4, wherein the charging station includes a plurality of the power transmitting devices, the vehicle includes a second electronic control unit, and each of the first electronic control unit of the charging station and the second electronic control unit of the vehicle is configured to, after completion of position alignment between any one of the plurality of power transmitting devices and the power receiving device, execute pairing process that identifies which one of the plurality of power transmitting devices has been subjected to the position alignment.

7. The contactless power transfer system according to claim 6, wherein

the second electronic control unit of the vehicle is configured to, after completion of the pairing process, determine whether a voltage received by the power receiving device exceeds a threshold, the second electronic control unit is configured to start receiving full-scale electric power when the received voltage exceeds the threshold, and the second electronic control unit is configured to set the threshold based on a smaller one of a permissible deviation of the primary coil in a horizontal direction and a permissible deviation of the secondary coil in the horizontal direction.

8. A charging station comprising:

a power transmitting device including a primary coil, the power transmitting device being configured to contactlessly transmit electric power to a power receiving device of a vehicle;

a receiving unit configured to receive information indicating a characteristic relating to a permissible power receiving range of a secondary coil included in the power receiving device; and

a first electronic control unit configured to determine in accordance with a determination criterion whether transfer of electric power from the power transmitting device to the power receiving device is appropriate, the determination criterion being determined based on the a characteristic relating to a pennissible power transmitting range of the primary coil and the characteristic relating to the permissible power receiving range of the secondary coil, a power transfer efficiency being higher than or equal to a predetermined value within the pennissible power transmitting range of the primary coil, and the power transfer efficiency being higlier than or equal to the predetemiined value within the permissible power receiving range of the secondary coil.

9. A vehicle comprising:

a power receiving device including a secondary coil, the power receiving device being configured to contactlessly receive electric power from a power transmitting device included in a charging station;

a receiving unit configured to receive information indicating a characteristic relating to a pennissible power transmitting range of a primary coil included in the power transmitting device; and

a second electronic control unit configured to determine in accordance with a determination criterion whether transfer of electric power from the power transmitting device to the power receiving device is appropriate, the determination criterion being determined based on the characteristic relating to the pennissible power transmitting range of the primary coil and a characteristic relating to a pennissible power receiving range of the secondary coil, a power transfer efficiency being higher than or equal to a predetennined value within the pennissible power transmitting range of the primary coil, and the power transfer efficiency being higher than or equal to the predetermined value within the pennissible power receiving range of the secondary coil.