Patent Description:
The present disclosure relates to a dynamic power supply system that supplies an electric power to a vehicle in motion.

Japanese Patent Application Laid-Open <CIT> discloses a wireless power reception device that wirelessly receives electric power while a vehicle is in motion. When a detection value based on a voltage generated in a power receiver of a wireless power reception device or a current flowing through the power receiver becomes a reference value or more, this system causes a charging operation of a power charger to start, and when the detection value falls below the reference value, this system causes the charging operation of the power charger to stop and supplies electric power from a capacitor unit to the power charger.

Furthermore, <CIT> discloses a method and apparatus for wirelessly charging an electric vehicle, comprising a communication receiver configured to obtain a request for a level of charging power to be delivered from a power antenna circuit to the electric vehicle via a charging field, and a controller operationally coupled to the communication receiver and configured to control a current or voltage generator of the power antenna circuit based on a power efficiency factor and the requested level of charging power. Still further, <CIT> refers to a wireless power supply/reception system wherein a vehicle controller pre-charges a capacitor connected to a power reception coil after the vehicle approaches a parking space, the vehicle controller acquires the identification data when the power transmission coil is in the first excitation, and transmits the acquired identification data to the ground unit. The ground controller pairs a power transmission device and a power reception device with each other if the identification data contained in the excitation pattern and the identification data acquired by the vehicle controller match each other.

However, a voltage to be stored in a capacitor of a power reception device varies with a voltage (inverter voltage) generated in a power-supply-side power supply device, which sometimes makes it difficult to determine whether a vehicle is at a position suitable for battery charging. It is also of concern that if the vehicle is not at the suitable position, an inverter circuit of the power supply device will cause an unnecessary current not contributing to battery charge to flow. This results in generation of a loss and, consequently, generation of a leakage magnetic field.

According to an aspect of the present disclosure, a dynamic power supply system in which electric power is supplied from a power supply device to a power reception device is provided. In the dynamic power supply system, the power supply device includes: an inverter circuit configured to output an alternating current; a power transmitter connected to the inverter circuit and configured to transmit an alternating-current electric power; a power-supply-side controller configured to control the inverter circuit; and a power-supply-side communicator, and the power reception device includes: a power receiver configured to receive the alternating-current electric power transmitted from the power transmitter; a rectifier circuit connected to the power receiver and configured to rectify the received alternating-current electric power; a DC-DC converter connected to the rectifier circuit and configured to convert and output a voltage; a battery connected to an output of the DC-DC converter; a load configured to operate with the received electric power; a power-receiving-side controller configured to control the DC-DC converter; and a power-receiving-side communicator configured to communicate with the power-supply-side communicator, wherein a period for performing pre-power-supply check prior to main power supply from the power supply device to the power reception device is provided, and the power-receiving-side controller is configured to: check a supplied electric power supplied from the power supply device to the power reception device, in a state where an effective value of an output voltage of the inverter circuit is fixed to a predetermined first voltage by the power-supply-side controller and an input voltage of the DC-DC converter is fixed to a predetermined second voltage by the power-receiving-side controller, in a pre-power-supply check, and cause, in response to the supplied electric power being equal to a predetermined electric power or more, the power supply device to start the main power supply. According to this aspect, it is possible to determine whether a vehicle is at a suitable position for battery charging and start main power supply without causing an unnecessary current not contributing to battery charge to flow.

As illustrated in <FIG>, a dynamic power supply system <NUM> includes a power supply device <NUM> on a road <NUM> side and a power reception device <NUM> on a vehicle <NUM> side. The dynamic power supply system <NUM> is a system enabling electric power to be supplied from the power supply device <NUM> to the vehicle <NUM> while the vehicle <NUM> is in motion. The vehicle <NUM> is in the form of, for example, an electric vehicle or a hybrid vehicle. In <FIG>, an x-axis direction represents a forward movement direction of the vehicle <NUM>, a y-axis direction represents a width direction of the vehicle <NUM>, and a z-axis direction is a vertically upward direction.

The power supply device <NUM> on the road <NUM> side includes a plurality of coils <NUM> for power transmission (hereinafter, also referred to as "power transmission coils <NUM>"), a plurality of power transmitter circuits <NUM> each of which supplies an alternating-current voltage to the corresponding one of the plurality of power transmission coils <NUM>, a plurality of vehicle position detectors <NUM> each provided for the corresponding one of the power transmitter circuits <NUM> or the power transmission coils <NUM>, a power source circuit <NUM> that supplies a direct-current voltage to the plurality of power transmitter circuits <NUM>, a power-supply-side controller <NUM>, a vehicle position detector <NUM>, and a power-supply-side communicator <NUM>.

The plurality of power transmission coils <NUM> are installed along the x-axis direction at a predetermined depth from a ground surface of the road <NUM>. Each power transmitter circuit <NUM>, which is a circuit that converts the direct-current voltage supplied from the power source circuit <NUM> to a high-frequency alternating-current voltage and applies it to the corresponding one of the power transmission coils <NUM>, includes an inverter circuit and a resonance circuit. It should be noted that each power transmitter circuit <NUM> may include a filter circuit in addition to the inverter circuit and the resonance circuit. Each power transmission coil <NUM> and the corresponding one of the power transmitter circuits <NUM> are collectively referred to as "a power supply segment SG" It should be noted that the power supply segment SG is sometimes simply referred to as "a segment SG" The power source circuit <NUM> is a circuit that supplies a direct-current electric power to the power transmitter circuits <NUM>. For example, the power source circuit <NUM> is in the form of an AC/DC converter circuit that rectifies an alternating current supplied from a commercial power source and outputs a direct current. It should be noted that the direct current outputted from the power source circuit <NUM> is not necessarily a completely direct current and may contain some fluctuations (ripples).

Each vehicle position detector <NUM> detects a position of the vehicle <NUM>. Each vehicle position detector <NUM> communicates with, for example, a vehicle-side position sensor <NUM> provided in the vehicle <NUM> and detects whether the vehicle <NUM> is on the segments SG by using a strength of the communication. The plurality of power transmitter circuits <NUM> perform power transmission using one or more of the power transmission coils <NUM> close to the vehicle <NUM> in accordance with the position of the vehicle <NUM> detected by the vehicle position detectors <NUM>. The power-supply-side controller <NUM> controls power supply from the segments SG It should be noted that each vehicle position detector <NUM> may detect the position of the vehicle <NUM> by using a camera, a search coil, or a laser.

The power-supply-side communicator <NUM> communicates with a power-receiving-side communicator <NUM> provided in the vehicle <NUM>. The communication includes, for example, instructions for power supply and instructions for main power supply.

The vehicle <NUM> includes a battery <NUM>, an auxiliary battery <NUM>, a power-receiving-side controller <NUM>, the vehicle-side position sensor <NUM>, a power reception circuit <NUM>, a power reception coil <NUM>, a DC/DC converter circuit <NUM>, an inverter circuit <NUM>, a motor generator <NUM>, and an auxiliary device <NUM>. The power reception coil <NUM> is connected to the power reception circuit <NUM> and an output of the power reception circuit <NUM> is connected to the battery <NUM>, a high-voltage side of the DC/DC converter circuit <NUM>, and the inverter circuit <NUM>. A low-voltage side of the DC/DC converter circuit <NUM> is connected to the auxiliary battery <NUM> and the auxiliary device <NUM>. The inverter circuit <NUM> is connected to the motor generator <NUM>.

The power reception coil <NUM> is a device that generates an induced electromotive force by electromagnetic induction between the power reception coil <NUM> and the power transmission coils <NUM>. The power reception circuit <NUM> includes a rectifier circuit that converts the alternating-current voltage outputted from the power reception coil <NUM> to a direct-current voltage and a DC/DC converter circuit that converts the direct-current voltage generated by the rectifier circuit to a voltage suitable for charging the battery <NUM>. The direct-current voltage outputted from the power reception circuit <NUM> is usable for charging the battery <NUM> and for driving the motor generator <NUM> via the inverter circuit <NUM>. The direct-current voltage is also usable for charging the auxiliary battery <NUM> and for driving the auxiliary device <NUM> as long as stepped down through the DC/DC converter circuit <NUM>. Alternatively, a plurality of power reception coils <NUM> may be installed. By virtue of the plurality of power reception coils <NUM> being installed, it is possible to provide a robust optimal design against misalignment of the vehicle <NUM>. Further, in a case where the plurality of power reception coils <NUM> are installed, the power reception circuit <NUM> may be polyphase. By virtue of being polyphase, the power reception circuit <NUM> can be provided as a single circuit and an installation space in the vehicle <NUM> can be reduced.

The battery <NUM> is a secondary battery that outputs a relatively high direct-current voltage for driving the motor generator <NUM>. The motor generator <NUM> operates as a three-phase alternating-current motor, generating a driving force for causing the vehicle <NUM> to travel. The motor generator <NUM> operates as a generator during deceleration of the vehicle <NUM>, regenerating electric power. With the motor generator <NUM> operating as a motor, the inverter circuit <NUM> converts electric power from the battery <NUM> to three-phase alternating current and supplies it to the motor generator <NUM>. With the motor generator <NUM> operating as a generator, the inverter circuit <NUM> converts the three-phase alternating current regenerated by the motor generator <NUM> to a direct current and supplies it to the battery <NUM>.

The DC/DC converter circuit <NUM> converts an output of the battery <NUM> to a voltage lower than an output voltage of the battery <NUM> and supplies it to the auxiliary battery <NUM> and the auxiliary device <NUM>. The auxiliary battery <NUM> is a secondary battery for driving the auxiliary device <NUM> and a voltage thereof is relatively low. The auxiliary device <NUM> includes a variety of peripherals of the vehicle <NUM>, such as an air conditioner, an electric power steering device, a headlight, a turn signal, and a wiper, and a variety of accessories of the vehicle <NUM>.

The power-receiving-side controller <NUM> controls the inverter circuit <NUM> inside the vehicle <NUM> and other components. In receiving dynamic non-contact power supply, the power-receiving-side controller <NUM> controls the power reception circuit <NUM>, performing a power receiving process.

As illustrated in <FIG>, the power supply device <NUM> on the road <NUM> side includes the power transmitter circuits <NUM> and the power transmission coils <NUM>. Each power transmitter circuit <NUM> includes an inverter circuit <NUM> and a resonance circuit <NUM>. The inverter circuit <NUM> includes four switching transistors Tr1 to Tr4, a capacitor C3, and four protection diodes D1 to D4. The four switching transistors Tr1 to Tr4 provide an H-bridge circuit. The switching transistors Tr1 and Tr3 are connected to each other in series, whereas the switching transistors Tr2 and Tr4 are connected to each other in series. The switching transistors Tr1, Tr2 are connected to a positive-side power source line V+, whereas the switching transistors Tr3, Tr4 are connected to a negative-side power source line V-. An intermediate node N1 between the switching transistors Tr1 and Tr3 and an intermediate node N2 between the switching transistors Tr2 and Tr4 are connected to the power transmission coil <NUM> through the resonance circuit <NUM>. Each of the switching transistors Tr1 to Tr4 is connected to the corresponding one of the protection diodes D1 to D4 in parallel. The capacitor C3 is a smoothing capacitor provided between the positive-side power source line V+ and a negative-side power source line V-. The switching transistors Tr2 and Tr3 are off while the switching transistors Tr1 and Tr4 are on, whereas the switching transistors Tr1 and Tr4 are off while the switching transistors Tr2 and Tr3 are on.

The resonance circuit <NUM> includes a capacitor C1 inserted in series between the power transmission coil <NUM> and the inverter circuit <NUM>. Thus, the resonance circuit <NUM> is in the form of a series resonance circuit in the present embodiment. It should be noted that the capacitor C1 may be in the form of a parallel resonance circuit connected to the power transmission coil <NUM> in parallel instead of a series resonance circuit.

As illustrated in <FIG>, a filter circuit may be provided between the inverter circuit <NUM> and the resonance circuit <NUM>. In a case where the resonance circuit <NUM> is a series resonance circuit, for example, a T-shaped filter circuit <NUM> including two coils and one capacitor may be used as the filter circuit. In contrast, in a case where the resonance circuit <NUM> is a parallel resonance circuit, the filter circuit may be a bandpass filter circuit <NUM> with a coil and a capacitor connected in series.

The vehicle-side power reception device <NUM> includes the power reception circuit <NUM> and the power reception coil <NUM>. The power reception circuit <NUM> includes a resonance circuit <NUM>, a rectifier circuit <NUM>, and a DC-DC converter circuit <NUM>. The resonance circuit <NUM> includes a capacitor C21 connected to the power reception coil <NUM> in series. Thus, the resonance circuit <NUM> is a series resonance circuit in the present embodiment. It should be noted that a parallel resonance circuit with the capacitor C21 connected to the power reception coil <NUM> in parallel may be used instead of a series resonance circuit. A filter circuit as in the power supply device <NUM> may be provided between the resonance circuit <NUM> and the rectifier circuit <NUM>.

The rectifier circuit <NUM>, which is a bridge rectifier circuit, includes four rectifier diodes D21 to D24 and a smoothing capacitor C23. The rectifier diodes D21 and D23 are connected to each other in series with an intermediate node N3 therebetween connected to the capacitor C21 of the resonance circuit <NUM>, whereas the rectifier diodes D22 and D24 are connected to each other in series with an intermediate node N4 therebetween connected to the power reception coil <NUM>. Respective cathodes of the rectifier diodes D21 and D22 are connected to a node Np, whereas respective anodes of the rectifier diodes D23 and D24 are connected to a node Nn. The smoothing capacitor C23 is connected to the node Np and the node Nn.

The DC-DC converter circuit <NUM> is a circuit that steps up or down the direct-current voltage rectified by the rectifier circuit <NUM> and supplies it to the battery <NUM>. The DC-DC converter circuit <NUM> includes four switching transistors Tr25 to Tr28, an inductor L28, protection diodes D25 to D28, and a smoothing capacitor C28. The switching transistors Tr25 and Tr27 are connected to each other in series between the node Np and the node Nn, whereas the switching transistors Tr26 and Tr28 are connected to each other in series. The inductor L28 is connected to an intermediate node N5 between the switching transistors Tr25 and Tr27 and an intermediate node N6 between the switching transistors Tr26 and Tr28. Each of the switching transistors Tr25 to Tr28 is connected to the corresponding one of the protection diodes D25 to D28 in parallel. The smoothing capacitor C28 is provided closer to the battery <NUM> than the four switching transistors Tr25 to Tr28.

The battery <NUM> is connected to the motor generator <NUM> through the inverter circuit <NUM>.

In a case where the vehicle <NUM> travels on a normal road with no segment SG installed as illustrated in <FIG>, all of the switching transistors Tr1 to Tr4 in the inverter circuit <NUM> of the power supply device <NUM> on the road <NUM> side are off. Thus, an output V1 from the inverter circuit <NUM> is zero and an output current I1 is also zero. In this case, no voltage is applied to the power transmission coil <NUM> and no current flows therethrough, so that neither voltage nor current is generated also in the power reception coil <NUM> of the vehicle <NUM>. An output voltage V2 from the rectifier circuit <NUM> is zero and an output current I2 from the rectifier circuit <NUM> is also zero.

Wishing to receive power supply to the vehicle <NUM>, a driver of the vehicle <NUM> makes a lane change from the normal road with no segment SG installed to a power supply road with the segments SG installed as illustrated in <FIG>. At time t1, the power-receiving-side controller <NUM> of the vehicle <NUM>, in response to detecting that the vehicle <NUM> moves to a position where an electric power can be supplied from the segments SG, performs pre-power-supply check. The power-receiving-side controller <NUM> may determine whether the position is available for power supply with reference to, for example, a strength of communication between the vehicle position detectors <NUM> and the vehicle-side position sensor <NUM>. In a case where signals of the vehicle position detectors <NUM> have directionality, the communication is possible as long as the vehicle-side position sensor <NUM> is within a specific range relative to the vehicle position detector <NUM>.

In the pre-power-supply check, the power-receiving-side controller <NUM> causes the power-supply-side controller <NUM> to fix an effective value V<NUM> of an output voltage of the inverter circuit <NUM> at a predetermined first voltage. The first voltage is a voltage lower than the output voltage of the inverter circuit <NUM> for performing main power supply. The power-supply-side controller <NUM> can set the effective value V<NUM> of the output voltage of the inverter circuit <NUM> to the predetermined first voltage by controlling a duty ratio of an output of the inverter circuit <NUM>. It should be noted that the first voltage is preferably a low value when a relative position relationship between the power transmission coil <NUM> and the power reception coil <NUM> is sufficient for power transfer and, if possible, should be set at a minimum sufficient for power transfer. This is for the purpose of preventing occurrence of unnecessary loss during the pre-power-supply check. Further, it is desirable that in setting the output voltage at the first voltage, a filtering process be performed in order to avoid a transitional change in current. As illustrated in <FIG>, to avoid a transitional phenomenon, a waveform of the effective value V1 of the output voltage at the time when the output voltage is fixed at the first voltage may be a simulated post-filtered waveform. The power-receiving-side controller <NUM> drives the switching transistors Tr25 to Tr28 of the DC-DC converter circuit <NUM>, thereby fixing an input voltage V<NUM> of the DC-DC converter circuit <NUM> at a second voltage. The second voltage, which is set from a power consumption of a load, i.e., the auxiliary device <NUM>, is set at a larger value with an increase in the power consumption of the device <NUM>. I<NUM> denotes an effective value of the output current of the inverter circuit <NUM> and I<NUM> denotes the output current of the rectifier circuit <NUM>. The currents I<NUM> and I<NUM> vary with a coupling coefficient k between the power transmission coil <NUM> and power reception coil. As illustrated in <FIG>, the vehicle <NUM> makes a lane change onto the segment SG, which increases the coupling coefficient k. It should be noted that P<NUM> denotes electric power to be supplied by the power supply device <NUM> and P<NUM> denotes electric power to be received by the power reception device <NUM>. P<NUM> = V<NUM>*I<NUM> and P<NUM> = V<NUM>*I<NUM>.

The voltages V<NUM> and V<NUM>, the currents I<NUM> and I<NUM>, an inductance L<NUM> and an electric resistance R<NUM> of the power transmission coil <NUM>, an inductance L<NUM> and an electric resistance R<NUM> of the power reception coil <NUM>, and the coupling coefficient k satisfy a relationship represented by the following mathematical expression (<NUM>). A mathematical expression (<NUM>) is derived by solving the mathematical expression (<NUM>) in terms of coupling coefficient k. In the mathematical expression (<NUM>), ω = 2πf, where f denotes a frequency of the inverter circuit <NUM>. Further, in the mathematical expression (<NUM>), a value of the coupling coefficient k, which is a value of <NUM> to <NUM>, varies with the relative position between the power transmission coil <NUM> and the power reception coil <NUM> and increases with the power transmission coil <NUM> and the power reception coil <NUM> becoming close to each other. <NUM>]
[Math. <NUM>] <MAT> [Math. <NUM>]
[Math. <NUM>] <MAT>.

With the vehicle <NUM> making a lane change onto a power supply road, the relative position between the power transmission coil <NUM> and the power reception coil <NUM> become close to each other and the coupling coefficient k increases. In other words, in this case, when V<NUM> is set constant, the output current I<NUM> increases. Then, at time t2, the output current I<NUM> of the rectifier circuit <NUM> exceeds a threshold Ith. The threshold Ith is a determination value for determining whether main power supply is to be performed. The power-receiving-side controller <NUM> sets the threshold Ith to a value represented by the following mathematical expression (<NUM>) using the power consumption Pa of the load, i.e., the auxiliary device <NUM>, a power transfer efficiency ηp, and a battery voltage Vb of the battery <NUM> at the time of start of the pre-power-supply check. The power transfer efficiency ηp, which is a total of a power transfer efficiency between the power transmission coil <NUM> and the power reception coil <NUM> and a conversion efficiency in the DC-DC converter circuit <NUM>, is experimentally obtainable.

By virtue of the threshold Ith being calculated and set in this manner, in a case where the output current I<NUM> of the rectifier circuit <NUM> exceeds the threshold Ith, the battery <NUM> can be charged with the electric power even though the load, i.e., the auxiliary device <NUM>, consumes the supplied electric power.

The power-receiving-side controller <NUM> provides, in response to detecting the output current I<NUM> of the rectifier circuit <NUM> exceeding the threshold Ith, instructions for the main power supply to the power-supply-side controller <NUM> through communication from the power-receiving-side communicator <NUM> via the power-supply-side communicator <NUM>. The main power supply is a process to be performed by the power-supply-side controller <NUM> to supply an electric power with the effective value V<NUM> of the output voltage of the inverter circuit <NUM> increased more than the first voltage. For example, the power-supply-side controller <NUM> increases the duty ratio of the inverter circuit <NUM> as compared with at the time t1, thereby making it possible to increase the effective value V<NUM> of the output voltage of the inverter circuit <NUM> more than the first voltage.

Description will be given of a flowchart of power reception to be performed by the power-receiving-side controller <NUM> with reference to <FIG>. When the power-receiving-side controller <NUM> detects that the vehicle <NUM> enters the power supply road based on a signal received by the vehicle-side position sensor <NUM> from the vehicle position detector <NUM> in Step S100, the process proceeds to step S110.

In step S110, the power-receiving-side controller <NUM> provides instructions for performing power supply for checking to the power-supply-side controller <NUM>. The instructions are provided through communication from the power-receiving-side communicator <NUM> via the power-supply-side communicator <NUM>.

In step S120, the power-receiving-side controller <NUM> fixes the input voltage of the DC-DC converter <NUM> to the predetermined second voltage by driving the DC-DC converter <NUM> and monitors the current I<NUM> flowing from the rectifier circuit. The pre-power-supply check is determined to be OK in response to the current I<NUM> being equal to the threshold Ith or more and the process proceeds to step S130. The pre-power-supply check is determined to be not OK in response to the current I<NUM> being less than the threshold Ith, the process proceeds to step S170.

In step S130, the power-receiving-side controller <NUM> provides instructions for the main power supply to the power-supply-side controller <NUM>.

In subsequent step S140, the power-receiving-side controller <NUM> determines whether the input current of the battery <NUM> is negative. The input current of the battery <NUM> being negative means that the battery <NUM> is not charged with an electric power but, inversely, an electric power is supplied from the battery <NUM>. The power-receiving-side controller <NUM> cause the process to proceed to step S190 in response to the input current of the battery <NUM> being negative and causes the process to proceed to step S150 in response to the input current of the battery <NUM> being not negative.

When the power-receiving-side controller <NUM> detects that the vehicle <NUM> moves out of the power supply road based on a signal received by the vehicle-side position sensor <NUM> from the vehicle position detector <NUM> in Step S150, the process proceeds to Step S160. In Step S160, the power-receiving-side controller <NUM> provides instructions for stopping power supply to the power-receiving-side controller <NUM>.

When the power-receiving-side controller <NUM> detects that the vehicle <NUM> moves out of the power supply road based on a signal received by the vehicle-side position sensor <NUM> from the vehicle position detector <NUM> in Step S170, the process proceeds to step S180. In step S180, the power-receiving-side controller <NUM> provides instructions for stopping the power supply for checking to the power-receiving-side controller <NUM>. This is because even though approaching the power supply road, the vehicle <NUM> may then move away therefrom. In a case where the vehicle <NUM> does not move out of the power supply road, the power-receiving-side controller <NUM> causes the process to proceed to step S120, continuing the pre-power-supply check.

In step S190, the power-receiving-side controller <NUM> provides instructions for stopping the power supply to the power-receiving-side controller <NUM> and then causes the process to proceed to step S110.

Description will be given of a flowchart of power supply to be performed by the power-supply-side controller <NUM> with reference to <FIG>. In response to receiving the instructions for power supply for checking from the power-receiving-side controller <NUM> (step S110) in Step S200, the power-supply-side controller <NUM> causes the process to proceed to step S210. In step S210, the power-supply-side controller <NUM> controls on/off of the switching transistors Tr1 to Tr4 of the inverter circuit <NUM> such that the output voltage V1 of the inverter circuit <NUM> reaches the first voltage.

In response to receiving the instructions for main power supply from the power-receiving-side controller <NUM> (Step S130) in Step S220, the power-supply-side controller <NUM> advances the process to Step S230. In response to receiving no instruction for main power supply, the power-supply-side controller <NUM> advances the process to Step S260.

In Step S230, the power-supply-side controller <NUM> controls on/off of the switching transistors Tr1 to Tr4 of the inverter circuit <NUM> such that the output voltage V1 of the inverter circuit <NUM> reaches a voltage for main power supply higher than the first voltage.

In response to receiving the instructions for stopping the power supply from the power-receiving-side controller <NUM> (step S160 or S190) in step S240, the power-supply-side controller <NUM> causes the process to proceeds to step S250, stopping the power supply. In response to receiving no instruction for stopping the power supply from the power-receiving-side controller <NUM> in step S240, the power-supply-side controller <NUM> causes the process to proceed to step S230, continuing the main power supply.

In response to receiving the instructions for stopping the power supply for checking from the power-receiving-side controller <NUM> (step S180) in step S260, the power-supply-side controller <NUM> causes the process to proceed to step S250, stopping the power supply. In response to receiving no instruction for stopping the power supply for checking from the power-receiving-side controller <NUM> in step S260, the power-supply-side controller <NUM> causes the process to proceed to step S210, continuing the power supply for checking.

Thus, in the present embodiment as described, it is possible to simply check whether an expected electric power is to be received and the battery <NUM> is to be charged with it in a state where the power-supply-side controller <NUM> fixes the effective value V<NUM> of the output voltage of the inverter circuit <NUM> to the predetermined first voltage and the power-receiving-side controller <NUM> fixes the input voltage V<NUM> of the DC-DC converter circuit <NUM> to the predetermined second voltage.

It should be noted that with the voltage V2 fixed, the received electric power is proportional to the current I<NUM>. Here, measurement of the current I<NUM> is easier than measurement of an electric power. Accordingly, the power-receiving-side controller <NUM> can easily determine whether to shift the main power supply by comparing the current I<NUM> outputted from the rectifier circuit <NUM> with the threshold Ith as described above. It should be noted that the power-receiving-side controller <NUM> may cause the power supply device <NUM> to start the main power supply in response to an electric power supplied from the power supply device <NUM> to the power reception device <NUM> during a pre-power-receiving check period becoming a predetermined electric power or more.

Further, in a case where electric power is to be supplied from the power supply device <NUM> to the power reception device <NUM>, the main power supply is not performed while the coupling coefficient k is small and the power transfer efficiency is low but started in response to the power transfer efficiency reaching a sufficient level. This makes it possible to improve a power supply efficiency as a whole.

It should be noted that in a case where the received electric power is to be consumed by the motor generator <NUM> not via the battery <NUM>, the power-receiving-side controller <NUM> may set the threshold Ith to a value represented by the following mathematical expression (<NUM>), where Pm denotes the power consumption of the motor generator <NUM>.

By virtue of the threshold Ith being calculated and set in this manner, in a case where the output current I<NUM> of the rectifier circuit <NUM> exceeds the threshold Ith, the battery <NUM> can be charged with the electric power even though the power consumption Pm of the motor generator <NUM> is taken into consideration.

The present embodiment is described by taking, as an example, a case where the power transmission coil <NUM> is provided as a power transmitter, the power reception coil <NUM> is provided as a power receiver, and an electric power is to be supplied from the power transmitter to the power receiver in a non-contact manner; however, a case where a power transmission terminal is provided as a power transmitter, a power receiving terminal is provided as a power receiver, and an electric power is to be supplied from the power transmitter to the power receiver with the power transmission terminal and the power receiving terminal being in contact with each other is also acceptable. In a contact-supply case, the coupling coefficient k is substantially <NUM> with an influence of resistance excluded. The power-receiving-side controller <NUM> can determine whether the main power supply is to be performed by providing instructions for power supply for checking and immediately comparing the current I<NUM> and the threshold Ith.

Claim 1:
A dynamic power supply system (<NUM>) in which an electric power is supplied from a power supply device (<NUM>) to a power reception device (<NUM>),
the power supply device comprising:
an inverter circuit (<NUM>) configured to output an alternating current;
a power transmitter (<NUM>) connected to the inverter circuit (<NUM>) and configured to transmit an alternating-current electric power;
a power-supply-side controller (<NUM>) configured to control the inverter circuit (<NUM>), and
a power-supply-side communicator (<NUM>),
the power reception device (<NUM>) comprising:
a power receiver (<NUM>) configured to receive the alternating-current electric power transmitted from the power transmitter (<NUM>);
a rectifier circuit (<NUM>) connected to the power receiver (<NUM>) and configured to rectify the received alternating-current electric power;
a DC-DC converter (<NUM>) connected to the rectifier circuit (<NUM>) and configured to convert and output a voltage;
a battery (<NUM>) connected to an output of the DC-DC converter (<NUM>);
a load (<NUM>) configured to operate with the received electric power;
a power-receiving-side controller (<NUM>) configured to control the DC-DC converter (<NUM>); and
a power-receiving-side communicator (<NUM>) configured to communicate with the power-supply-side communicator (<NUM>), wherein
a period for performing pre-power-supply check prior to main power supply from the power supply device (<NUM>) to the power reception device (<NUM>) is provided,
characterized in that
the power-receiving-side controller (<NUM>) is configured to:
check a supplied electric power supplied from the power supply device (<NUM>) to the power reception device (<NUM>), in a state where an effective value of an output voltage of the inverter circuit (<NUM>) is fixed to a predetermined first voltage by the power-supply-side controller (<NUM>) and an input voltage of the DC-DC converter is fixed to a predetermined second voltage by the power-receiving-side controller (<NUM>), in the pre-power-supply check, and
cause, in response to the supplied electric power being equal to a predetermined electric power or more, the power supply device (<NUM>) to start the main power supply.