Patent Description:
Hitherto, there is known a technology for contactless transmission of electric power between a ground-side device provided on the ground and a mobile body such as a vehicle using a transmission method such as magnetic field coupling (electromagnetic induction), electric field coupling, magnetic field resonance coupling (magnetic field resonance), or electric field resonance coupling (electric field resonance). Particularly in contactless electric power transmission of magnetic field resonance coupling using a transmission-side resonance circuit and a reception-side resonance circuit having the same resonance frequency, large electric power can be transmitted via an alternating current magnetic field generated in the transmission-side resonance circuit even if the mobile body and the ground-side device are located away from each other.

However, constant generation of the alternating current magnetic field for electric power transmission between the ground-side device and the mobile body leads to a waste of electric power. There is also concern about influence of the alternating current magnetic field on electronic devices or the like. Therefore, it is desirable to generate the alternating current magnetic field for electric power transmission at an appropriate timing when the mobile body passes over the ground-side device.

In this regard, <CIT> (<CIT>) describes that, when a power supply request is wirelessly transmitted from a vehicle, a power supply device embedded in a road contactlessly transmits electric power to the vehicle while the vehicle passes over the road.

<CIT> discusses wireless charging for vehicle batteries.

<CIT> discusses a power receiving device, a parking assist system, and a power transfer system.

<CIT> discusses a method and apparatus for a wireless charging system.

<CIT> discusses a method and apparatus for positioning a motor vehicle above a ground plate. <CIT> discloses a position estimation method to be applied to a contactless power supply system configured to perform contactless electric power transmission of magnetic field resonance coupling between a ground-side device and a mobile body, the contactless power supply system including an alternating current magnetic field generation circuit provided in the ground-side device, a magnetic field detector provided in the mobile body, a transmission-side resonance circuit provided in the mobile body wherein a plurality of the magnetic field detectors is provided along a direction perpendicular to a travelling direction of the mobile body, and a reception-side resonance circuit provided in the ground side device.

In a case where the approach of the vehicle to the ground-side device is detected by wireless communication, however, there is a possibility that the alternating current magnetic field cannot be generated at the appropriate timing due to hindrance to the wireless communication by an obstacle or the like. When the transmission-side resonance circuit and the reception-side resonance circuit are misaligned while the mobile body such as a vehicle is passing over the ground-side device, the efficiency of electric power transmission decreases.

The present invention provides a contactless power supply system, a position estimation method, a mobile body, and a power supply device in which a relative positional relationship between a transmission-side resonance circuit and a reception-side resonance circuit is accurately detected during contactless electric power transmission of magnetic field resonance coupling between the mobile body and a ground-side device.

According to the contactless power supply system, the position estimation method, the mobile body, and the power supply device of the present invention, the relative positional relationship between the transmission-side resonance circuit and the reception-side resonance circuit can accurately be detected during the contactless electric power transmission of magnetic field resonance coupling between the mobile body and the ground-side device.

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following description, like constituent elements are denoted by like reference numerals.

A first example of the present invention will be described below with reference to <FIG>.

<FIG> is a diagram schematically illustrating a configuration of a contactless power supply system <NUM> according to the first embodiment of the present invention. The contactless power supply system <NUM> performs contactless electric power transmission of magnetic field resonance coupling (magnetic field resonance) between a ground-side device <NUM> and a vehicle <NUM>. Particularly in the present example the contactless power supply system <NUM> performs the contactless electric power transmission between the ground-side device <NUM> and the vehicle <NUM> while the vehicle <NUM> is traveling. The ground-side device <NUM> is an example of a power supply device, and the vehicle <NUM> is an example of a mobile body. The contactless electric power transmission is also referred to as "contactless power supply", "wireless electric power transmission", or "wireless power supply".

The contactless power supply system <NUM> includes a power transmission device <NUM> configured to contactlessly transmit electric power, and a power reception device <NUM> configured to contactlessly receive the electric power from the power transmission device <NUM>. In the present embodiment, the power transmission device <NUM> is mounted on the ground-side device <NUM>, and the power reception device <NUM> is mounted on the vehicle <NUM>. That is, the ground-side device <NUM> performs contactless power supply to the vehicle <NUM>, and the contactless power supply system <NUM> contactlessly transmits electric power from the ground-side device <NUM> to the vehicle <NUM>.

As illustrated in <FIG>, the ground-side device <NUM> includes a power supply <NUM> and a controller <NUM> in addition to the power transmission device <NUM>. The ground-side device <NUM> is provided on a road where the vehicle <NUM> passes, and is, for example, embedded in the ground (under the road surface). At least a part of the ground-side device <NUM> (for example, the power supply <NUM> and the controller <NUM>) may be arranged above the road surface.

The power supply <NUM> is an electric power source of the power transmission device <NUM> and supplies electric power to the power transmission device <NUM>. Examples of the power supply <NUM> include a commercial alternating current power supply that supplies singlephase alternating current power. The power supply <NUM> may be, for example, an alternating current power supply that supplies three-phase alternating current power.

The power transmission device <NUM> includes a transmission-side rectifier circuit <NUM>, an inverter <NUM>, and a transmission-side resonance circuit <NUM>. In the power transmission device <NUM>, appropriate alternating current power (high-frequency power) is supplied to the transmission-side resonance circuit <NUM> via the transmission-side rectifier circuit <NUM> and the inverter <NUM>.

The transmission-side rectifier circuit <NUM> is electrically connected to the power supply <NUM> and the inverter <NUM>. The transmission-side rectifier circuit <NUM> rectifies alternating current power supplied from the power supply <NUM> to convert the alternating current power into direct current power, and supplies the direct current power to the inverter <NUM>. Examples of the transmission-side rectifier circuit <NUM> include an alternating current-direct current converter.

The inverter <NUM> is electrically connected to the transmission-side rectifier circuit <NUM> and the transmission-side resonance circuit <NUM>. The inverter <NUM> converts the direct current power supplied from the transmission-side rectifier circuit <NUM> into alternating current power (high-frequency power) having a frequency higher than that of the alternating current power of the power supply <NUM>, and supplies the high-frequency power to the transmission-side resonance circuit <NUM>.

The transmission-side resonance circuit <NUM> includes a resonator including a coil <NUM> and capacitors <NUM>. Various parameters of the coil <NUM> and the capacitors <NUM> (outside diameter and bore diameter of the coil <NUM>, number of turns of the coil <NUM>, capacitance of the capacitors <NUM>, etc.) are determined so that the resonance frequency of the transmission-side resonance circuit <NUM> reaches a predetermined set value. The predetermined set value is, for example, <NUM> to <NUM>, preferably <NUM> defined by the SAE TIR J2954 standard as a frequency band for contactless electric power transmission.

The transmission-side resonance circuit <NUM> is arranged at the center of a lane where the vehicle <NUM> passes to position the center of the coil <NUM> at the center of the lane. When the high-frequency power supplied from the inverter <NUM> is applied to the transmission-side resonance circuit <NUM>, the transmission-side resonance circuit <NUM> generates an alternating current magnetic field for transmitting the electric power. The power supply <NUM> may be a direct current power supply such as a fuel cell or a solar cell. In this case, the transmission-side rectifier circuit <NUM> may be omitted.

The controller <NUM> is, for example, a general-purpose computer, and performs various types of control on the ground-side device <NUM>. For example, the controller <NUM> is electrically connected to the inverter <NUM> of the power transmission device <NUM> and controls the inverter <NUM> to control the electric power transmission by the power transmission device <NUM>.

<FIG> is a schematic configuration diagram of the controller <NUM>. The controller <NUM> includes a memory <NUM> and a processor <NUM>. The memory <NUM> and the processor <NUM> are connected to each other via a signal line. The controller <NUM> may further include, for example, a communication interface that enables communication between the ground-side device <NUM> and the outside of the ground-side device <NUM>. The controller <NUM> is an example of a control device of the ground-side device <NUM>.

The memory <NUM> includes, for example, a volatile semiconductor memory (for example, a random-access memory (RAM)) and a non-volatile semiconductor memory (for example, a read-only memory (ROM)). The memory <NUM> stores, for example, programs to be executed by the processor <NUM>, and various types of data to be used when various processes are executed by the processor <NUM>.

The processor <NUM> includes one or more central processing units (CPUs) and their peripheral circuits, and executes various processes. The processor <NUM> may further include an arithmetic circuit such as a logical operation unit or a numerical operation unit.

As illustrated in <FIG>, the vehicle <NUM> includes a motor <NUM>, a battery <NUM>, a power control unit (PCU) <NUM>, and an electronic control unit (ECU) <NUM> in addition to the power reception device <NUM>. In the present embodiment, the vehicle <NUM> is a battery electric vehicle (BEV) that is not equipped with an internal combustion engine, and the motor <NUM> outputs traveling power.

The motor <NUM> is, for example, an alternating current synchronous motor, and functions as an electric motor and a generator. When the motor <NUM> functions as the electric motor, the motor <NUM> is driven by using electric power stored in the battery <NUM> as a power source. The output of the motor <NUM> is transmitted to wheels <NUM> via reducers and axles. When the vehicle <NUM> is decelerated, the motor <NUM> is driven by rotation of the wheels <NUM>, and the motor <NUM> functions as the generator to generate regenerative electric power.

The battery <NUM> is a rechargeable secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. The battery <NUM> stores electric power necessary for the vehicle <NUM> to travel (for example, driving electric power of the motor <NUM>). When the regenerative electric power generated by the motor <NUM> is supplied to the battery <NUM>, the battery <NUM> is charged and the charge ratio (state of charge (SOC)) of the battery <NUM> is recovered. The battery <NUM> may be charged by an external power supply other than the ground-side device <NUM> via a charging port provided in the vehicle <NUM>.

The PCU <NUM> is electrically connected to the battery <NUM> and the motor <NUM>. The PCU <NUM> includes an inverter, a boost converter, and a direct current-direct current converter. The inverter converts direct current power supplied from the battery <NUM> into alternating current power, and supplies the alternating current power to the motor <NUM>. The inverter converts alternating current power (regenerative electric power) generated by the motor <NUM> into direct current power, and supplies the direct current power to the battery <NUM>. The boost converter boosts a voltage of the battery <NUM> as needed when the electric power stored in the battery <NUM> is supplied to the motor <NUM>. The direct current-direct current converter steps down the voltage of the battery <NUM> when the electric power stored in the battery <NUM> is supplied to an electronic device such as a headlight.

The power reception device <NUM> includes a reception-side resonance circuit <NUM>, a reception-side rectifier circuit <NUM>, and a charging circuit <NUM>. The power reception device <NUM> receives electric power from the power transmission device <NUM> and supplies the received electric power to the battery <NUM>.

The reception-side resonance circuit <NUM> is arranged at the bottom of the vehicle <NUM> to reduce a distance from a road surface. In the present embodiment, the reception-side resonance circuit <NUM> is arranged at the center of the vehicle <NUM> in a vehicle width direction, and is arranged between front wheels <NUM> and rear wheels <NUM> in a fore-and-aft direction of the vehicle <NUM>.

The reception-side resonance circuit <NUM> has the same configuration as that of the transmission-side resonance circuit <NUM>, and includes a resonator including a coil <NUM> and capacitors <NUM>. Various parameters of the coil <NUM> and the capacitors <NUM> (outside diameter and bore diameter of the coil <NUM>, number of turns of the coil <NUM>, capacitance of the capacitors <NUM>, etc.) are determined so that the resonance frequency of the reception-side resonance circuit <NUM> agrees with the resonance frequency of the transmission-side resonance circuit <NUM>. When the amount of deviation between the resonance frequency of the reception-side resonance circuit <NUM> and the resonance frequency of the transmission-side resonance circuit <NUM> is small, for example, when the resonance frequency of the reception-side resonance circuit <NUM> is within a range of ±<NUM>% of the resonance frequency of the transmission-side resonance circuit <NUM>, the resonance frequency of the reception-side resonance circuit <NUM> need not agree with the resonance frequency of the transmission-side resonance circuit <NUM>.

When the alternating current magnetic field is generated in the transmission-side resonance circuit <NUM> while the reception-side resonance circuit <NUM> faces the transmission-side resonance circuit <NUM> as illustrated in <FIG>, oscillation of the alternating current magnetic field is transmitted to the reception-side resonance circuit <NUM> that resonates at the same resonance frequency as that of the transmission-side resonance circuit <NUM>. As a result, an induced current flows in the reception-side resonance circuit <NUM> by electromagnetic induction, and electric power is generated in the reception-side resonance circuit <NUM> by the induced current. That is, the transmission-side resonance circuit <NUM> transmits electric power to the reception-side resonance circuit <NUM>, and the reception-side resonance circuit <NUM> receives the electric power from the transmission-side resonance circuit <NUM>.

The reception-side rectifier circuit <NUM> is electrically connected to the reception-side resonance circuit <NUM> and the charging circuit <NUM>. The reception-side rectifier circuit <NUM> rectifies alternating current power supplied from the reception-side resonance circuit <NUM> to convert the alternating current power into direct current power, and supplies the direct current power to the charging circuit <NUM>. Examples of the reception-side rectifier circuit <NUM> include an alternating current-direct current converter.

The charging circuit <NUM> is electrically connected to the reception-side rectifier circuit <NUM> and the battery <NUM>. The charging circuit <NUM> converts the direct current power supplied from the reception-side rectifier circuit <NUM> into direct current power at a voltage level of the battery <NUM> and supplies the direct current power to the battery <NUM>. When the electric power transmitted from the power transmission device <NUM> is supplied to the battery <NUM> by the power reception device <NUM>, the battery <NUM> is charged and the SOC of the battery <NUM> is recovered. Examples of the charging circuit <NUM> include a direct current-direct current converter.

The ECU <NUM> performs various types of control on the vehicle <NUM>. For example, the ECU <NUM> is electrically connected to the charging circuit <NUM> of the power reception device <NUM> and controls the charging circuit <NUM> to control the charging of the battery <NUM> with the electric power transmitted from the power transmission device <NUM>. The ECU <NUM> is electrically connected to the PCU <NUM> and controls the PCU <NUM> to control the transfer of the electric power between the battery <NUM> and the motor <NUM>.

<FIG> is a schematic configuration diagram of the ECU <NUM>. The ECU <NUM> includes a communication interface <NUM>, a memory <NUM>, and a processor <NUM>. The communication interface <NUM>, the memory <NUM>, and the processor <NUM> are connected to each other via a signal line.

The communication interface <NUM> includes an interface circuit for connecting the ECU <NUM> to an in-vehicle network conforming to a standard such as a controller area network (CAN).

The memory <NUM> includes, for example, a volatile semiconductor memory (for example, a RAM) and a non-volatile semiconductor memory (for example, a ROM). The memory <NUM> stores, for example, programs to be executed by the processor <NUM>, and various types of data to be used when various processes are executed by the processor <NUM>.

As illustrated in <FIG>, the vehicle <NUM> further includes a global navigation satellite system (GNSS) receiver <NUM>, a map database <NUM>, and a communication device <NUM>. The GNSS receiver <NUM>, the map database <NUM>, and the communication device <NUM> are electrically connected to the ECU <NUM>.

The GNSS receiver <NUM> detects a current position of the vehicle <NUM> (for example, a latitude and longitude of the vehicle <NUM>) based on positioning information obtained from a plurality of (for example, three or more) positioning satellites. Specifically, the GNSS receiver <NUM> captures the positioning satellites and receives radio waves transmitted from the positioning satellites. Then, the GNSS receiver <NUM> calculates a distance to each positioning satellite based on a difference between a transmission time and a reception time of the radio wave, and detects a current position of the vehicle <NUM> based on the distance to the positioning satellite and the position of the positioning satellite (orbit information). The output of the GNSS receiver <NUM>, that is, the current position of the vehicle <NUM> detected by the GNSS receiver <NUM> is transmitted to the ECU <NUM>.

The global navigation satellite system (GNSS) is a generic term for satellite positioning systems such as the Global Positioning System (GPS) in the United States, the Global Navigation Satellite System (GLONASS) in Russia, Galileo in Europe, the Quasi-Zenith Satellite System (QZSS) in Japan, BeiDou in China, and the Indian Regional Navigation Satellite System (IRNSS) in India. Therefore, the GNSS receiver <NUM> includes a GPS receiver.

The map database <NUM> stores map information. The map information includes, for example, position information of an installation area of the ground-side device <NUM>. The ECU <NUM> acquires the map information from the map database <NUM>. The map database <NUM> may be provided outside the vehicle <NUM> (for example, in a server), and the ECU <NUM> may acquire the map information from the outside of the vehicle <NUM>.

The communication device <NUM> is a device that enables communication between the vehicle <NUM> and the outside of the vehicle <NUM> (for example, a road-to-vehicle communication device or a data communication module (DCM)). The ECU <NUM> communicates with the outside of the vehicle <NUM> via the communication device <NUM>.

As described above, the contactless power supply system <NUM> transmits the electric power from the ground-side device <NUM> to the vehicle <NUM> via the alternating current magnetic field generated in the transmission-side resonance circuit <NUM> of the power transmission device <NUM>. However, constant generation of the alternating current magnetic field for electric power transmission between the ground-side device <NUM> and the vehicle <NUM> leads to a waste of electric power. There is also concern about influence of the alternating current magnetic field on electronic devices or the like.

Therefore, it is desirable to generate the alternating current magnetic field for electric power transmission at an appropriate timing when the vehicle <NUM> passes over the ground-side device <NUM>. In a case where the approach of the vehicle <NUM> to the ground-side device <NUM> is detected by wireless communication, however, there is a possibility that the alternating current magnetic field cannot be generated at the appropriate timing due to hindrance to the wireless communication by an obstacle or the like. When the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM> are misaligned while the vehicle <NUM> is passing over the ground-side device <NUM>, the efficiency of electric power transmission decreases.

In the present example the contactless power supply system <NUM> includes an alternating current magnetic field generation circuit <NUM> and a magnetic field detector <NUM>, and detects a relative positional relationship between the transmission-side resonance circuit <NUM> of the power transmission device <NUM> and the reception-side resonance circuit <NUM> of the power reception device <NUM> by using the alternating current magnetic field generation circuit <NUM> and the magnetic field detector <NUM>. In the present example, as illustrated in <FIG>, the alternating current magnetic field generation circuit <NUM> is provided in the vehicle <NUM>, and the magnetic field detector <NUM> is provided in the ground-side device <NUM>.

The alternating current magnetic field generation circuit <NUM> generates an alternating current magnetic field for detecting the relative positional relationship between the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM> (hereinafter referred to as "position detecting alternating current magnetic field"). The alternating current magnetic field generation circuit <NUM> is arranged at the bottom of the vehicle <NUM> to reduce a distance from a road surface. In the present example, the alternating current magnetic field generation circuit <NUM> is arranged at the center of the vehicle <NUM> in the vehicle width direction, and is arranged behind the reception-side resonance circuit <NUM> in the fore-and-aft direction of the vehicle <NUM>. The alternating current magnetic field generation circuit <NUM> may be arranged at the same position as that of the reception-side resonance circuit <NUM> or in front of the reception-side resonance circuit <NUM> in the fore-and-aft direction of the vehicle <NUM>.

The alternating current magnetic field generation circuit <NUM> has the same configuration as those of the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM>, and includes a resonator including a coil <NUM> and capacitors <NUM>. Various parameters of the coil <NUM> and the capacitors <NUM> (outside diameter and bore diameter of the coil <NUM>, number of turns of the coil <NUM>, capacitance of the capacitors <NUM>, etc.) are determined so that the resonance frequency of the alternating current magnetic field generation circuit <NUM> reaches a predetermined set value. The predetermined set value is set to a value different from the resonance frequencies of the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM>, that is, the resonance frequency of magnetic field resonance coupling.

As illustrated in <FIG>, the alternating current magnetic field generation circuit <NUM> is electrically connected to the PCU <NUM>, and the ECU <NUM> controls the alternating current magnetic field generation circuit <NUM> via the PCU <NUM>. The inverter of the PCU <NUM> converts the direct current power supplied from the battery <NUM> into alternating current power and supplies the alternating current power to the alternating current magnetic field generation circuit <NUM> based on a command from the ECU <NUM>. When the alternating current power supplied from the PCU <NUM> is applied to the alternating current magnetic field generation circuit <NUM>, the alternating current magnetic field generation circuit <NUM> generates the position detecting alternating current magnetic field. That is, the alternating current magnetic field generation circuit <NUM> generates the alternating current magnetic field as a position signal of the vehicle <NUM>.

For example, the ECU <NUM> controls the PCU <NUM> to generate the position detecting alternating current magnetic field by the alternating current magnetic field generation circuit <NUM> when the distance between the installation area of the ground-side device <NUM> and the vehicle <NUM> is equal to or smaller than a predetermined value. The distance between the installation area of the ground-side device <NUM> and the vehicle <NUM> is calculated by, for example, comparing the current position of the vehicle <NUM> detected by the GNSS receiver <NUM> and the position of the installation area of the ground-side device <NUM> stored in the map database <NUM>. When a predetermined signal is received from a road-side unit provided before the ground-side device <NUM> via the communication device <NUM>, the ECU <NUM> may control the PCU <NUM> to generate the position detecting alternating current magnetic field by the alternating current magnetic field generation circuit <NUM>. The ECU <NUM> may constantly generate a feeble alternating current magnetic field by the alternating current magnetic field generation circuit <NUM> while the vehicle <NUM> is traveling. The ECU <NUM> may control the alternating current magnetic field generation circuit <NUM> via an inverter provided separately from the PCU <NUM>.

The alternating current magnetic field generated by the alternating current magnetic field generation circuit <NUM> as the position signal of the vehicle <NUM> may include identification information of the vehicle <NUM> (for example, a vehicle identifier (ID)). That is, the vehicle <NUM> may transmit the identification information of the vehicle <NUM> to the ground-side device <NUM> via the alternating current magnetic field in addition to the position signal of the vehicle <NUM>. In this case, the ECU <NUM> of the vehicle <NUM> transmits the position signal and the identification information of the vehicle <NUM> to the ground-side device <NUM> by, for example, modulating the alternating current magnetic field based on the identification information of the vehicle <NUM> when generating the alternating current magnetic field by the alternating current magnetic field generation circuit <NUM>.

The magnetic field detector <NUM> detects a magnetic field around the ground-side device <NUM>. Examples of the magnetic field detector <NUM> include a magneto-impedance (MI) sensor. Driving electric power of the magnetic field detector <NUM> is supplied to the magnetic field detector <NUM> from, for example, the power supply <NUM> via a drive circuit. The magnetic field detector <NUM> may be a Hall sensor, a magneto-resistive (MR) sensor, or the like.

The magnetic field detector <NUM> is arranged before the transmission-side resonance circuit <NUM> of the power transmission device <NUM> in the traveling direction of the vehicle <NUM> on a road provided with the power transmission device <NUM>, and is arranged at the center of a lane where the vehicle <NUM> passes. The magnetic field detector <NUM> is arranged in the ground (below a road surface) or above the road surface. When the position detecting alternating current magnetic field is generated from the vehicle <NUM> around the magnetic field detector <NUM>, the magnetic field detector <NUM> detects the position detecting alternating current magnetic field.

The magnetic field detector <NUM> is electrically connected to the controller <NUM>, and the output of the magnetic field detector <NUM> is transmitted to the controller <NUM>. In the present embodiment, the contactless power supply system <NUM> includes the controller <NUM>, and the controller <NUM> controls the contactless power supply between the ground-side device <NUM> and the vehicle <NUM>.

<FIG> is a functional block diagram of the processor <NUM> of the controller <NUM>. In the present embodiment, the processor <NUM> includes a position estimator <NUM> and a power supply controller <NUM>. The position estimator <NUM> and the power supply controller <NUM> are functional modules implemented by the processor <NUM> of the controller <NUM> executing a computer program stored in the memory <NUM> of the controller <NUM>. The position estimator <NUM> and the power supply controller <NUM> may be implemented by a dedicated arithmetic circuit provided in the processor <NUM>.

The position estimator <NUM> estimates the relative positional relationship between the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM> based on the output of the magnetic field detector <NUM>. Specifically, the position estimator <NUM> extracts an alternating current magnetic field of a specific frequency from the output of the magnetic field detector <NUM>, and estimates the relative positional relationship between the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM> based on the extracted alternating current magnetic field of the specific frequency. The specific frequency is a frequency of the AC magnetic field generated from the vehicle <NUM> as the position signal, and corresponds to a frequency of the alternating current magnetic field to be detected. That is, the position estimator <NUM> estimates the relative positional relationship between the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM> by detecting the position detecting alternating current magnetic field generated from the alternating current magnetic field generation circuit <NUM>.

In the present embodiment, the influence of obstacles in the transmission and reception of signals can be reduced by using the alternating current magnetic field as the position detecting signal. Even when a stationary magnetic field (direct current magnetic field) is generated by a metal or the like present around the ground-side device <NUM>, it is easy to distinguish the stationary magnetic field and the position detecting signal (alternating current magnetic field).

In the present embodiment, the frequency of the position detecting alternating current magnetic field is different from the resonance frequencies of the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM>. Therefore, it is easy to distinguish the alternating current magnetic field generated in the transmission-side resonance circuit <NUM> for electric power transmission and the alternating current magnetic field generated in the alternating current magnetic field generation circuit <NUM> for position detection. By using the alternating current magnetic field having the frequency different from that of the alternating current magnetic field for electric power transmission as the position detecting signal, the relative positional relationship between the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM> can be detected accurately.

The frequency of the position detecting alternating current magnetic field is preferably set to a value lower than the resonance frequencies of the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM>. Thus, the position detecting alternating current magnetic field can be generated more easily. For example, when the resonance frequencies of the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM> are <NUM>, the frequency of the position detecting alternating current magnetic field is set to <NUM> to <NUM>, for example, <NUM>.

In the present example the transmission-side resonance circuit <NUM> and the magnetic field detector <NUM> are provided in the ground-side device <NUM>, and the reception-side resonance circuit <NUM> and the alternating current magnetic field generation circuit <NUM> are provided in the vehicle <NUM>. That is, the transmission-side resonance circuit <NUM> and the magnetic field detector <NUM> are provided in one of the vehicle <NUM> and the ground-side device <NUM>, and the reception-side resonance circuit <NUM> and the alternating current magnetic field generation circuit <NUM> are provided in the other of the vehicle <NUM> and the ground-side device <NUM>. In this case, the source of the electric power transmission alternating current magnetic field and the source of the position detecting alternating current magnetic field are different. Therefore, the temporal change in the signal strength detected by the magnetic field detector <NUM> differs between the position detecting alternating current magnetic field and the electric power transmission alternating current magnetic field. As a result, the position detecting alternating current magnetic field and the electric power transmission alternating current magnetic field can be distinguished more easily, and furthermore, the relative positional relationship between the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM> can be detected more accurately.

When the alternating current magnetic field generated by the alternating current magnetic field generation circuit <NUM> includes the identification information of the vehicle <NUM>, the position estimator <NUM> acquires the identification information of the vehicle <NUM> from the output of the magnetic field detector <NUM>. Thus, the vehicle <NUM> to be supplied with electric power can be identified. As a result, the vehicle <NUM> can easily be, for example, billed for a power supply fee.

The power supply controller <NUM> controls the contactless electric power transmission between the ground-side device <NUM> and the vehicle <NUM> based on the relative positional relationship between the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM> estimated by the position estimator <NUM>. That is, the power supply controller <NUM> controls the electric power transmission from the transmission-side resonance circuit <NUM> of the power transmission device <NUM> to the reception-side resonance circuit <NUM> of the power reception device <NUM> based on the estimation result from the position estimator <NUM>. For example, the power supply controller <NUM> starts the electric power transmission from the transmission-side resonance circuit <NUM> to the reception-side resonance circuit <NUM> when the position estimator <NUM> detects that the vehicle <NUM> including the reception-side resonance circuit <NUM> is approaching the ground-side device <NUM>.

The control flow described above will be described below with reference to a flowchart of <FIG> is a flowchart illustrating a control routine of a power supply process according to the first example of the present invention. This control routine is repeatedly executed by the processor <NUM> of the controller <NUM>.

In Step S101, the position estimator <NUM> first acquires an output of the magnetic field detector <NUM>.

In Step S102, the position estimator <NUM> determines, based on the output of the magnetic field detector <NUM>, whether the vehicle <NUM> is approaching the ground-side device <NUM>, that is, whether the reception-side resonance circuit <NUM> is approaching the transmission-side resonance circuit <NUM>. For example, the position estimator <NUM> performs frequency analysis on the output of the magnetic field detector <NUM> to extract a frequency component of the position detecting alternating current magnetic field, and determines that the vehicle <NUM> is approaching the ground-side device <NUM> when the value (peak value) of the extracted frequency component is equal to or larger than a predetermined value. Examples of the method for the frequency analysis include Fourier transform.

When determination is made in Step S102 that the vehicle <NUM> is not approaching the ground-side device <NUM>, this control routine is terminated. When determination is made in Step S102 that the vehicle <NUM> is approaching the ground-side device <NUM>, this control routine proceeds to Step S103.

In Step S103, the power supply controller <NUM> transmits electric power from the ground-side device <NUM> to the vehicle <NUM>. Specifically, the power supply controller <NUM> controls the inverter <NUM> of the power transmission device <NUM> to supply high-frequency power to the transmission-side resonance circuit <NUM>, thereby transmitting the electric power from the transmission-side resonance circuit <NUM> to the reception-side resonance circuit <NUM>.

For example, the power supply controller <NUM> transmits the electric power from the transmission-side resonance circuit <NUM> to the reception-side resonance circuit <NUM> for a predetermined period. The predetermined period is determined in advance in consideration of a period for the vehicle <NUM> to pass over the ground-side device <NUM>. The power supply controller <NUM> may stop the electric power transmission from the transmission-side resonance circuit <NUM> to the reception-side resonance circuit <NUM> when the passage of the vehicle <NUM> over the ground-side device <NUM> is detected. In this case, for example, the magnetic field detectors <NUM> are provided in front of and behind the transmission-side resonance circuit <NUM> in the traveling direction of the vehicle <NUM>, and the passage of the vehicle <NUM> over the ground-side device <NUM> is detected based on the output of the magnetic field detector <NUM> in front of the transmission-side resonance circuit <NUM>. The passage of the vehicle <NUM> may be detected by, for example, road-to-vehicle communication between the vehicle <NUM> and a road-side unit. After Step S103, this control routine is terminated.

The configuration and control of a contactless power supply system according to the second embodiment are basically the same as the configuration and control of the contactless power supply system according to the first embodiment except for points described below. Therefore, the second embodiment of the present invention will be described below focusing on the differences from the first embodiment.

<FIG> is a diagram schematically illustrating a part of a configuration of a contactless power supply system <NUM>' according to the second embodiment of the present invention. In the second embodiment, the contactless power supply system <NUM>' further includes a filter circuit <NUM> that filters the output of the magnetic field detector <NUM>.

The filter circuit <NUM> is provided between the magnetic field detector <NUM> and the controller <NUM> in the ground-side device <NUM>, and is electrically connected to the magnetic field detector <NUM> and the controller <NUM>. The filter circuit <NUM> passes a signal having the frequency of the position detecting alternating current magnetic field and attenuates a signal having the resonance frequency of each of the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM>.

The position estimator <NUM> of the controller <NUM> acquires the output of the magnetic field detector <NUM> filtered by the filter circuit <NUM>, that is, the output of the magnetic field detector <NUM> corresponding to the frequency component of the position detecting alternating current magnetic field. Then, the position estimator <NUM> estimates the relative positional relationship between the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM> based on the filtered output of the magnetic field detector <NUM>. Therefore, in the second embodiment, the frequency analysis for the magnetic field detector <NUM> is omitted or simplified, thereby reducing the calculation load on the controller <NUM> for position detection.

When the frequency of the position detecting alternating current magnetic field is higher than the resonance frequencies of the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM>, for example, a high-pass filter (HPF) is used as the filter circuit <NUM>. When the frequency of the position detecting alternating current magnetic field is lower than the resonance frequencies of the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM>, for example, a low-pass filter (LPF) is used as the filter circuit <NUM>. The filter circuit <NUM> may be a bandpass filter (BPF) that passes only signals in a specific frequency band that includes the frequency of the position detecting alternating current magnetic field and does not include the frequency of the electric power transmission alternating current magnetic field. Thus, the frequency component of the position detecting alternating current magnetic field can be extracted more accurately from the output of the magnetic field detector <NUM>.

Also in the second embodiment, the control routine of <FIG> is executed. In Step S101, the position estimator <NUM> acquires the output of the magnetic field detector <NUM> filtered by the filter circuit <NUM>. In Step S102, the position estimator <NUM> determines whether the vehicle <NUM> is approaching the ground-side device <NUM> based on the filtered output of the magnetic field detector <NUM>.

Next, a third embodiment of the present invention will be described. The configuration and control of a contactless power supply system according to the third embodiment are basically the same as the configuration and control of the contactless power supply system according to the first example except for points described below. Therefore, the third embodiment of the present invention will be described below focusing on the differences from the first example.

<FIG> is a diagram illustrating an example of arrangement of the magnetic field detectors <NUM> according to the third embodiment of the present invention. In the third embodiment, a plurality of magnetic field detectors <NUM> is provided along a direction perpendicular to the traveling direction of the vehicle <NUM>. That is, the contactless power supply system <NUM> includes the plurality of magnetic field detectors <NUM>, and the magnetic field detectors <NUM> are provided in the ground-side device <NUM>. The magnetic field detectors <NUM> are spaced away from each other along the direction perpendicular to the traveling direction of the vehicle <NUM>. For example, the magnetic field detectors <NUM> are arranged at equal intervals along the direction perpendicular to the traveling direction of the vehicle <NUM>.

As described above, the reception-side resonance circuit <NUM> and the alternating current magnetic field generation circuit <NUM> provided in the vehicle <NUM> are arranged at the center of the vehicle <NUM> in the vehicle width direction, and the transmission-side resonance circuit <NUM> is arranged at the center of a lane where the vehicle <NUM> passes to position the center of the coil <NUM> at the center of the lane. Therefore, one of the magnetic field detectors <NUM> is arranged at the center of the lane where the vehicle <NUM> passes. Thus, one of the magnetic field detectors <NUM> is arranged at the same position as that of the transmission-side resonance circuit <NUM> in the direction perpendicular to the traveling direction of the vehicle <NUM>. In the example of <FIG>, the magnetic field detector <NUM> is arranged at the center of the lane, and the magnetic field detectors <NUM> are arranged on the right and left sides of the central magnetic field detector <NUM>. Therefore, a total of three magnetic field detectors <NUM> are arranged at equal intervals.

When the reception-side resonance circuit <NUM> and the transmission-side resonance circuit <NUM> are misaligned while the vehicle <NUM> is passing over the ground-side device <NUM>, that is, when the vehicle <NUM> is traveling with displacement from the center of the lane, the efficiency of electric power transmission from the transmission-side resonance circuit <NUM> to the reception-side resonance circuit <NUM> decreases. In the third embodiment, the power supply controller <NUM> prohibits the electric power transmission from the transmission-side resonance circuit <NUM> to the reception-side resonance circuit <NUM> when the reception-side resonance circuit <NUM> and the transmission-side resonance circuit <NUM> are misaligned in the direction perpendicular to the traveling direction of the vehicle <NUM>. As a result, it is possible to suppress the transmission of electric power while the efficiency of electric power transmission decreases, and furthermore, reduce the waste of power consumption in the power transmission device <NUM>.

<FIG> is a flowchart illustrating a control routine of a power supply process according to the third embodiment of the present invention. This control routine is repeatedly executed by the processor <NUM> of the controller <NUM>.

In Step S201, the position estimator <NUM> first acquires outputs of the magnetic field detectors <NUM>.

In Step S202, the position estimator <NUM> determines whether the vehicle <NUM> is approaching the ground-side device <NUM> similarly to Step S102 in <FIG>. For example, the position estimator <NUM> determines that the vehicle <NUM> is approaching the ground-side device <NUM> when the value (peak value) of the frequency component of the position detecting alternating current magnetic field in the output of at least one of the magnetic field detectors <NUM> is equal to or larger than the predetermined value.

When determination is made in Step S202 that the vehicle <NUM> is not approaching the ground-side device <NUM>, this control routine is terminated. When determination is made in Step S202 that the vehicle <NUM> is approaching the ground-side device <NUM>, this control routine proceeds to Step S203.

In Step S203, the position estimator <NUM> determines whether the reception-side resonance circuit <NUM> and the transmission-side resonance circuit <NUM> are misaligned in the direction perpendicular to the traveling direction of the vehicle <NUM>. For example, the position estimator <NUM> determines that the reception-side resonance circuit <NUM> and the transmission-side resonance circuit <NUM> are misaligned when the output of the magnetic field detector <NUM> arranged at the center of the lane is not maximum among the outputs of the magnetic field detectors <NUM>, that is, when the output of the magnetic field detector <NUM> arranged at a position other than the center of the lane is maximum. The position estimator <NUM> may determine that the reception-side resonance circuit <NUM> and the transmission-side resonance circuit <NUM> are misaligned when the output of the magnetic field detector <NUM> arranged on the outermost side in a width direction of the lane is maximum. The position estimator <NUM> may calculate an amount of misalignment between the reception-side resonance circuit <NUM> and the transmission-side resonance circuit <NUM> based on the outputs of the magnetic field detectors <NUM>, and determine that the reception-side resonance circuit <NUM> and the transmission-side resonance circuit <NUM> are misaligned when the calculated misalignment amount is equal to or larger than a predetermined value.

When determination is made in Step S203 that the reception-side resonance circuit <NUM> and the transmission-side resonance circuit <NUM> are misaligned, this control routine is terminated. That is, the electric power transmission from the transmission-side resonance circuit <NUM> to the reception-side resonance circuit <NUM> is prohibited when the vehicle <NUM> passes over the ground-side device <NUM>.

When determination is made in Step S203 that the reception-side resonance circuit <NUM> and the transmission-side resonance circuit <NUM> are not misaligned, this control routine proceeds to Step S204. In Step S204, the power supply controller <NUM> transmits electric power from the ground-side device <NUM> to the vehicle <NUM> similarly to Step S103 in <FIG>. After Step S204, this control routine is terminated.

Next, a fourth embodiment of the present invention will be described. The configuration and control of a contactless power supply system according to the fourth embodiment are basically the same as the configuration and control of the contactless power supply system according to the first example except for points described below. Therefore, the fourth embodiment of the present invention will be described below focusing on the differences from the first example.

<FIG> is a diagram illustrating an example of arrangement of the magnetic field detectors <NUM> and the transmission-side resonance circuits <NUM> according to the fourth embodiment of the present invention. In the fourth embodiment, the magnetic field detectors <NUM> are provided along the direction perpendicular to the traveling direction of the vehicle <NUM> similarly to the third embodiment.

In the fourth embodiment, a plurality of transmission-side resonance circuits <NUM> of the power transmission device <NUM> as well as the magnetic field detectors <NUM> is provided along the direction perpendicular to the traveling direction of the vehicle <NUM>. That is, the contactless power supply system <NUM> includes the plurality of transmission-side resonance circuits <NUM>, and the transmission-side resonance circuits <NUM> are provided in the ground-side device <NUM>. The transmission-side resonance circuits <NUM> are spaced away from each other along the direction perpendicular to the traveling direction of the vehicle <NUM>. For example, the transmission-side resonance circuits <NUM> are arranged at equal intervals along the direction perpendicular to the traveling direction of the vehicle <NUM>.

As described above, the reception-side resonance circuit <NUM> provided in the vehicle <NUM> is arranged at the center of the vehicle <NUM> in the vehicle width direction. Therefore, one of the transmission-side resonance circuits <NUM> is arranged at the center of a lane of the road where the vehicle <NUM> passes. In the example of <FIG>, the transmission-side resonance circuit <NUM> is arranged at the center of the lane, and the transmission-side resonance circuits <NUM> are arranged on the right and left sides of the central transmission-side resonance circuit <NUM>. Therefore, a total of three transmission-side resonance circuits <NUM> are arranged at equal intervals. That is, the number of transmission-side resonance circuits <NUM> is equal to the number of magnetic field detectors <NUM>.

When the plurality of transmission-side resonance circuits <NUM> is arranged in the vehicle width direction, the transmission-side resonance circuit <NUM> closest to the reception-side resonance circuit <NUM> provided in the vehicle <NUM> differs depending on a lateral position of the vehicle <NUM>. For example, when the vehicle <NUM> is traveling with displacement to the right in the traveling direction, the right transmission-side resonance circuit <NUM> is closest to the reception-side resonance circuit <NUM>. When the vehicle <NUM> is traveling with displacement to the left in the traveling direction, the left transmission-side resonance circuit <NUM> is closest to the reception-side resonance circuit <NUM>.

In the fourth embodiment, the power supply controller <NUM> switches the transmission-side resonance circuit <NUM> that transmits electric power to the reception-side resonance circuit <NUM> based on the relative positional relationship between the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM> in the direction perpendicular to the traveling direction of the vehicle <NUM>. As a result, it is possible to suppress the decrease in the efficiency of electric power transmission due to the misalignment between the reception-side resonance circuit <NUM> and the transmission-side resonance circuit <NUM>, and furthermore, reduce the waste of power consumption in the power transmission device <NUM>.

<FIG> is a flowchart illustrating a control routine of a power supply process according to the fourth embodiment of the present invention. This control routine is repeatedly executed by the processor <NUM> of the controller <NUM>.

Steps S301 and S302 are executed similarly to Steps S201 and S202 in <FIG>. When determination is made in Step S302 that the vehicle <NUM> is approaching the ground-side device <NUM>, this control routine proceeds to Step S303.

In Step S303, the position estimator <NUM> determines whether the output of the magnetic field detector <NUM> on the right side in the traveling direction of the vehicle <NUM> is larger than the output of the magnetic field detector <NUM> at the center of the lane in terms of the frequency component of the position detecting alternating current magnetic field. When determination is made that the output of the right magnetic field detector <NUM> is equal to or smaller than the output of the central magnetic field detector <NUM>, this control routine proceeds to Step S304.

In Step S304, the position estimator <NUM> determines whether the output of the magnetic field detector <NUM> on the left side in the traveling direction of the vehicle <NUM> is larger than the output of the magnetic field detector <NUM> at the center of the lane in terms of the frequency component of the position detecting alternating current magnetic field. When determination is made that the output of the left magnetic field detector <NUM> is equal to or smaller than the output of the central magnetic field detector <NUM>, that is, when the output of the central magnetic field detector <NUM> is maximum, the position estimator <NUM> determines that the vehicle <NUM> is not displaced and this control routine proceeds to Step S305.

In Step S305, the power supply controller <NUM> transmits electric power from the transmission-side resonance circuit <NUM> at the center of the lane to the reception-side resonance circuit <NUM>. Specifically, the power supply controller <NUM> controls the inverter <NUM> of the power transmission device <NUM> to supply high-frequency power to the transmission-side resonance circuit <NUM> at the center of the lane. After Step S305, this control routine is terminated.

When determination is made in Step S303 that the output of the right magnetic field detector <NUM> is larger than the output of the central magnetic field detector <NUM>, the position estimator <NUM> determines that the vehicle <NUM> is displaced to the right in the traveling direction and this control routine proceeds to Step S306. In Step S306, the power supply controller <NUM> transmits electric power from the transmission-side resonance circuit <NUM> on the right side in the traveling direction of the vehicle <NUM> to the reception-side resonance circuit <NUM>. Specifically, the power supply controller <NUM> controls the inverter <NUM> of the power transmission device <NUM> to supply high-frequency power to the right transmission-side resonance circuit <NUM>. After Step S306, this control routine is terminated.

When determination is made in Step S304 that the output of the left magnetic field detector <NUM> is larger than the output of the central magnetic field detector <NUM>, the position estimator <NUM> determines that the vehicle <NUM> is displaced to the left in the traveling direction and this control routine proceeds to Step S307. In Step S307, the power supply controller <NUM> transmits electric power from the transmission-side resonance circuit <NUM> on the left side in the traveling direction of the vehicle <NUM> to the reception-side resonance circuit <NUM>. Specifically, the power supply controller <NUM> controls the inverter <NUM> of the power transmission device <NUM> to supply high-frequency power to the left transmission-side resonance circuit <NUM>. After Step S307, this control routine is terminated.

In Step S305, the power supply controller <NUM> may transmit the electric power from all the transmission-side resonance circuits <NUM> to the reception-side resonance circuit <NUM>. In Step S306, the power supply controller <NUM> may transmit the electric power to the reception-side resonance circuit <NUM> from the transmission-side resonance circuit <NUM> on the right side in the traveling direction of the vehicle <NUM> and the transmission-side resonance circuit <NUM> at the center of the lane. In Step S307, the power supply controller <NUM> may transmit the electric power to the reception-side resonance circuit <NUM> from the transmission-side resonance circuit <NUM> on the left side in the traveling direction of the vehicle <NUM> and the transmission-side resonance circuit <NUM> at the center of the lane.

Next, an embodiment of the present invention will be described. The configuration and control of a contactless power supply system according to the embodiment are basically the same as the configuration and control of the contactless power supply system according to the first example except for points described below. Therefore, the fifth embodiment of the present invention will be described below focusing on the differences from the first example.

<FIG> is a diagram schematically illustrating a configuration of a contactless power supply system <NUM>" according to the embodiment of the present invention. As described above, the battery <NUM> of the vehicle <NUM> can be charged with the regenerative electric power generated by the motor <NUM>. When the SOC of the battery <NUM> is high, however, the regenerative electric power cannot be supplied to the battery <NUM>. When the SOC of the battery <NUM> is kept high, deterioration of the battery <NUM> is advanced. Therefore, there is a need to reduce the SOC of the battery <NUM> while the vehicle <NUM> is traveling.

In the embodiment, the power transmission device <NUM> is mounted on the vehicle <NUM> and the power reception device <NUM> is mounted on the ground-side device <NUM> unlike the first example. That is, the contactless power supply system <NUM>" contactlessly transmits the electric power from the vehicle <NUM> to the ground-side device <NUM> while the vehicle <NUM> is traveling.

In the embodiment, the power transmission device <NUM> includes the inverter <NUM> and the transmission-side resonance circuit <NUM>. The battery <NUM> is used as the electric power source of the power transmission device <NUM>, and the electric power of the battery <NUM> is consumed by electric power transmission from the vehicle <NUM> to the ground-side device <NUM>.

The inverter <NUM> is electrically connected to the battery <NUM> and the transmission-side resonance circuit <NUM>. The inverter <NUM> converts the direct current power supplied from the battery <NUM> into high-frequency power, and supplies the high-frequency power to the transmission-side resonance circuit <NUM>. When the high-frequency power supplied from the inverter <NUM> is applied to the transmission-side resonance circuit <NUM>, the transmission-side resonance circuit <NUM> generates an alternating current magnetic field for transmitting the electric power. The ECU <NUM> is electrically connected to the inverter <NUM> of the power transmission device <NUM> and controls the inverter <NUM> to control the electric power transmission by the power transmission device <NUM>. The inverter <NUM> may be omitted and the PCU <NUM> may electrically be connected to the transmission-side resonance circuit <NUM> to function as an inverter of the power transmission device <NUM>.

The power reception device <NUM> includes the reception-side resonance circuit <NUM>, the reception-side rectifier circuit <NUM>, and the charging circuit <NUM> similarly to the first embodiment. The ground-side device <NUM> includes a storage battery <NUM>, and the electric power transmitted from the power transmission device <NUM> to the power reception device <NUM> is supplied to the storage battery <NUM>. The storage battery <NUM> is a rechargeable secondary battery such as a lithium-ion battery or a nickel-metal hydride battery.

The charging circuit <NUM> is electrically connected to the reception-side rectifier circuit <NUM> and the storage battery <NUM>. The charging circuit <NUM> converts the direct current power supplied from the reception-side rectifier circuit <NUM> into direct current power at a voltage level of the storage battery <NUM> and supplies the direct current power to the storage battery <NUM>. When the electric power transmitted from the power transmission device <NUM> is supplied to the storage battery <NUM> by the power reception device <NUM>, the storage battery <NUM> is charged.

In the embodiment, the alternating current magnetic field generation circuit <NUM> is provided in the ground-side device <NUM>, and the magnetic field detector <NUM> is provided in the vehicle <NUM>. The alternating current magnetic field generation circuit <NUM> is arranged at the center of the lane where the vehicle <NUM> passes, and is arranged before the reception-side resonance circuit <NUM> in the traveling direction of the vehicle <NUM>. The alternating current magnetic field generation circuit <NUM> may be arranged at the same position as that of the reception-side resonance circuit <NUM> or in front of the reception-side resonance circuit <NUM> in the traveling direction of the vehicle <NUM>.

The ground-side device <NUM> includes an inverter <NUM>, and the alternating current magnetic field generation circuit <NUM> generates the position detecting alternating current magnetic field by using electric power supplied from the inverter <NUM>. The inverter <NUM> is electrically connected to the storage battery <NUM> and the alternating current magnetic field generation circuit <NUM>. The controller <NUM> is electrically connected to the inverter <NUM> and controls the alternating current magnetic field generation circuit <NUM> via the inverter <NUM>.

The inverter <NUM> converts the direct current power supplied from the storage battery <NUM> into alternating current power and supplies the alternating current power to the alternating current magnetic field generation circuit <NUM> based on a command from the controller <NUM>. When the alternating current power supplied from the inverter <NUM> is applied to the alternating current magnetic field generation circuit <NUM>, the alternating current magnetic field generation circuit <NUM> generates the position detecting alternating current magnetic field.

For example, when a road-side unit provided before the ground-side device <NUM> detects the vehicle <NUM> and the controller <NUM> receives a signal from the road-side unit, the controller <NUM> controls the inverter <NUM> to generate the position detecting alternating current magnetic field by the alternating current magnetic field generation circuit <NUM>. The controller <NUM> may constantly generate a feeble alternating current magnetic field by the alternating current magnetic field generation circuit <NUM> in a predetermined time frame (for example, a time frame other than nighttime) or all day long.

As illustrated in <FIG>, the magnetic field detector <NUM> is arranged in front of the transmission-side resonance circuit <NUM> in the vehicle <NUM>. The magnetic field detector <NUM> is electrically connected to the ECU <NUM>, and the output of the magnetic field detector <NUM> is transmitted to the ECU <NUM>. In the embodiment, the contactless power supply system <NUM>" includes the ECU <NUM>, and the ECU <NUM> controls the contactless power supply between the ground-side device <NUM> and the vehicle <NUM>.

<FIG> is a functional block diagram of the processor <NUM> of the ECU <NUM>. In the present embodiment, the processor <NUM> includes the position estimator <NUM> and the power supply controller <NUM>. The position estimator <NUM> and the power supply controller <NUM> are functional modules implemented by the processor <NUM> of the ECU <NUM> executing a computer program stored in the memory <NUM> of the ECU <NUM>. The position estimator <NUM> and the power supply controller <NUM> may be implemented by a dedicated arithmetic circuit provided in the processor <NUM>.

<FIG> is a flowchart illustrating a control routine of a power supply process according to the embodiment of the present invention. This control routine is repeatedly executed by the processor <NUM> of the ECU <NUM>.

Steps S401 and S402 are executed similarly to Steps S101 and S102 in <FIG>. When determination is made in Step S402 that the vehicle <NUM> is approaching the ground-side device <NUM>, this control routine proceeds to Step S403.

In Step S403, the power supply controller <NUM> determines whether the SOC of the battery <NUM> of the vehicle <NUM> is equal to or higher than a predetermined value. The predetermined value is set to, for example, an upper limit of a value at which the regenerative electric power can be collected.

The SOC of the battery <NUM> is calculated by a known method. For example, a battery sensor for detecting state parameters of the battery <NUM> is provided in the battery <NUM>, and the power supply controller <NUM> calculates the SOC of the battery <NUM> based on a voltage and temperature of the battery <NUM> detected by the battery sensor. The power supply controller <NUM> may calculate the SOC of the battery <NUM> by integrating input and output currents of the battery <NUM> detected by the battery sensor. The power supply controller <NUM> may calculate the SOC of the battery <NUM> by using a state estimation method such as a Kalman filter.

When determination is made in Step S403 that the SOC of the battery <NUM> is lower than the predetermined value, this control routine is terminated. When determination is made in Step S403 that the SOC of the battery <NUM> is equal to or higher than the predetermined value, this control routine proceeds to Step S404.

In Step S404, the power supply controller <NUM> transmits electric power from the vehicle <NUM> to the ground-side device <NUM>. Specifically, similarly to Step S103 in <FIG>, the power supply controller <NUM> controls the inverter <NUM> of the power transmission device <NUM> to supply high-frequency power to the transmission-side resonance circuit <NUM>, thereby transmitting the electric power from the transmission-side resonance circuit <NUM> to the reception-side resonance circuit <NUM>. After Step S404, this control routine is terminated.

Next, other embodiments of the present invention will be described. Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various revisions and modifications may be made within the scope of the claims. For example, the configurations of the resonators of the transmission-side resonance circuit <NUM>, the reception-side resonance circuit <NUM>, and the alternating current magnetic field generation circuit <NUM> are only illustrative. For example, the numbers of capacitors <NUM>, <NUM>, and <NUM> may be one. Since the alternating current magnetic field generation circuit <NUM> that generates the position detecting alternating current magnetic field need not use the magnetic field resonance coupling, the capacitors <NUM> may be omitted.

The vehicle <NUM> may be a hybrid electric vehicle (HEV) or a plug-in hybrid electric vehicle (PHEV) including an internal combustion engine and a motor as traveling power sources. The vehicle <NUM> may be an autonomous driving vehicle in which at least a part of acceleration, steering, and deceleration (braking) of the vehicle <NUM> is controlled autonomously. The mobile body that transfers electric power with the ground-side device <NUM> may be a commercial vehicle such as a bus or a truck, an automated guided vehicle (AGV), a drone, or the like.

In the first example illustrated in <FIG>, the alternating current magnetic field generation circuit <NUM> may be provided in the ground-side device <NUM>, and the magnetic field detector <NUM> and the position estimator <NUM> may be provided in the vehicle <NUM>. In this case, for example, the relative positional relationship between the transmission-side resonance circuit <NUM> and the reception-side resonance circuit <NUM> estimated by the position estimator <NUM> based on the output of the magnetic field detector <NUM> is presented to a driver via a display device (human-machine interface (HMI) or the like) of the vehicle <NUM>. As a result, the driver can, for example, decelerate or steer the vehicle <NUM> as necessary to increase the amount of electric power transmission. The vehicle <NUM> may automatically be controlled to increase the amount of electric power transmission based on the estimation result from the position estimator <NUM>.

The examples and embodiment described above may be implemented in any combination. For example, in the third to fifth embodiments, the filter circuit <NUM> may be provided between the magnetic field detector <NUM> and the controller <NUM> or between the magnetic field detector <NUM> and the ECU <NUM> similarly to the second example.

Claim 1:
A position estimation method to be applied to a contactless power supply system (<NUM>, <NUM>', <NUM>") configured to perform contactless electric power transmission of magnetic field resonance coupling between a ground-side device (<NUM>) and a mobile body (<NUM>), the contactless power supply system (<NUM>) including an alternating current magnetic field generation circuit (<NUM>) provided in the ground-side device, a magnetic field detector (<NUM>) provided in the mobile body, a transmission-side resonance circuit (<NUM>) provided in the mobile body wherein a plurality of the magnetic field detectors (<NUM>) is provided along a direction perpendicular to a traveling direction of the mobile body (<NUM>), and a reception-side resonance circuit (<NUM>) provided in the ground side device, the position estimation method comprising:
generating an alternating current magnetic field by the alternating current magnetic field generation circuit (<NUM>);
detecting the alternating current magnetic field by the magnetic field detector (<NUM>); and
estimating, based on an output of the magnetic field detectors (<NUM>), a relative positional relationship between the transmission-side resonance circuit (<NUM>) that transmits electric power and the reception-side resonance circuit (<NUM>) that receives the electric power from the transmission-side resonance circuit (<NUM>), wherein a frequency of the alternating current magnetic field is different from a resonance frequency of each of the transmission-side resonance circuit (<NUM>) and the reception-side resonance circuit (<NUM>);
controlling, with a power supply controller (<NUM>), the contactless electric power transmission based on the estimated relative positional relationship;
providing a plurality of the transmission-side resonance circuits (<NUM>) along the direction perpendicular to the traveling direction of the mobile body (<NUM>);
estimating the relative positional relationship based on the transmission-side resonance circuit (<NUM>), of the plurality of the transmission-side resonance circuits (<NUM>), closest to the reception-side resonance circuit (<NUM>) provided in the ground-side device, and
switching, with the power supply controller, the transmission-side resonance circuit (<NUM>) that transmits the electric power to the reception-side resonance circuit (<NUM>) based on the relative positional relationship in the direction perpendicular to the traveling direction of the mobile body (<NUM>).