CONTACTLESS POWER FEEDING APPARATUS AND CONTACTLESS POWER FEEDING METHOD

A contactless power feeding system includes power supply lines to supply power in a contactless manner to a power receiver on a mobile body, power supply boards to generate power, and a power distribution circuit to distribute and supply the power generated by the power supply boards to the power supply lines.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to contactless power feeding apparatuses and contactless power feeding methods.

2. Description of the Related Art

For example, as a conventional contactless power feeding system, a system described in WO2013/145573 is known. The contactless power feeding n described in WO2013/145573 includes a power supply line and a power feeding apparatus configured to supply power to the power supply line from a power feeding point. In such a configuration, a mobile body such as a transport cart can receive power from the power supply line in a contactless manner.

SUMMARY OF THE INVENTION

In the conventional contactless power feeding system described above, when power supply from the power feeding apparatus is stopped due to a failure or the like, it is impossible to prevent power supply to a mobile body from the power supply line connected to the power feeding apparatus.

Example embodiments of the present invention provide contactless power feeding apparatuses and contactless power feeding methods each capable of stably supplying power to a mobile body.

A contactless power feeding apparatus according to an example embodiment of the present disclosure includes a plurality of power supply lines to supply power in a contactless manner to a power receiver provided on a mobile body, a plurality of power supply boards to generate power, and a power distribution circuit to distribute and supply the power generated by the power supply boards to the power supply lines.

According to the above example embodiment, the power generated by each of the power supply boards is distributed and supplied to the power supply lines. Hence, it is possible to supply power to a mobile body from the power supply lines in a contactless manner. Consequently, even if the power supply from one of the power supply boards is stopped due to a failure or the like, it is possible to supply power via the power supply lines to the mobile body from the remaining power supply boards other than the one of the power supply boards. Hence, it is possible to stably supply power to the mobile body.

Alternatively, a contactless power feeding method according to another example embodiment of the present disclosure distributes and supplies power generated by a plurality of power supply boards to a plurality of power supply lines via a power distribution circuit, and supplies the power to a power receiver provided on a mobile body from the power supply lines in a contactless manner. Based on a clock signal generated therein, one power supply board set to a first operation mode that is one of the power supply boards, generates AC power by driving an inverter circuit of the one power supply board, and transmits the clock signal as a standard signal to remaining power supply boards other than the one power supply board among the power supply boards, and, based on a clock signal generated therein and the standard signal received from the one power supply board, the remaining power supply boards generate AC power by driving the inverter circuit such that a phase of the AC power output from the one power supply board matches a phase of the AC power output from the remaining power supply boards.

According to the other example embodiment described above, in the one power supply board set to the first operation mode in advance, AC power is generated on the basis of the clock signal of the one power supply board, and in the remaining power supply boards set to a second operation mode in advance, AC power the phase of which matches that of the AC power generated by the one power supply board is generated on the basis of the clock signal of the remaining power supply board and the clock signal in the one power supply board. Consequently, it is possible to align the phases of the AC power supplied to the power supply lines from the power supply boards, and stably supply power to the mobile body. In addition, by performing synchronous control on the basis of a clock signal to control the inverter circuit, there is no need to take variation factors into account. Hence, it is possible to more stably supply power.

According to example embodiments of the present disclosure, it is possible to stably supply power to a mobile body.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

Hereinafter, example embodiments of the present disclosure will be described with reference to the accompanying drawings. In the description of the drawings, the same reference numerals denote the same components, and overlapping descriptions will be omitted.

FIG.1is a circuit diagram illustrating a configuration of a contactless power feeding system100serving as a contactless power feeding apparatus according to an example embodiment of the present disclosure. As illustrated inFIG.1, the contactless power feeding system100in the present example embodiment is a power feeding system configured to supply power in a contactless manner to a mobile body130including a power receiver120. An example of the mobile body130to which power is supplied by the contactless power feeding system100includes a tracked transport vehicle with a built-in motor that travels on a track such as rails by driving the motor with power received via the power receiver120such as a power receiving coil. The contactless power feeding system100of the present example embodiment includes a plurality of power supply boards10, a power distribution circuit11, and a plurality of power supply lines12. In the present example embodiment, a configuration including three power supply boards10A,10B, and10C, and three power supply lines12A,12B, and12C are illustrated. However, the number of the power supply boards10and the number of power supply lines12are not limited to a specific number as long as the number is two or more. The power distribution circuit11may be provided outside the power supply boards10as a separate device, or may be built into any power supply board10.

Each of the power supply boards10A,10B, and10C is a device configured to generate AC power by receiving a supply of constant voltage (DC voltage) from a DC power source, and has a pair of output terminals13configured to output AC power. The pair of output terminals13of the power supply boards10A,10B, and10C are electrically connected to the power distribution circuit11.

The power distribution circuit11is a circuit configured to distribute AC power generated by the three power supply boards10A,10B, and10C each to the three power supply lines12A,12B, and12C, and combine and supply the distributed AC power to each of the three power supply lines12A,12B, and12C. The power distribution circuit11includes a circuit unit configured to distribute and combine the AC power, and a resonance circuit configured to cause the AC power to resonate and be output (details will be described later).

The power supply lines12A,12B, and12C are transmission lines provided along a track (not illustrated) where the mobile body130can travel. That is, the power supply lines12A,12B, and12C are arranged in parallel or substantially in parallel in a state of being electrically insulated from each other on the track, which is not illustrated. The power supply lines12A,12B, and12C each include a pair of transmission lines14extending in parallel, and ends of the pair of transmission lines14are electrically connected to the power distribution circuit11. These power supply lines12A,12B, and12C supply the AC power output from the power distribution circuit11, to the mobile body130via the power receiver120located in the vicinity of the pair of transmission lines14. Specifically, the power receiver120including an E-shaped core is attached to the mobile body130, and the pair of transmission lines14are disposed in a gap of the E-shaped core of the power receiver120.

Next, with reference toFIG.2andFIG.3, a detailed configuration of the contactless power feeding system100will be described.FIG.2is a diagram illustrating a detailed configuration of the contactless power feeding system100inFIG.1.FIG.3is a diagram illustrating a detailed configuration of an inverter circuit inFIG.2and the connection configuration.

Each of the power supply boards10A,10B, and10C includes a synchronous circuit15, an inverter circuit16, and a pair of inductor elements17aand17b.

The inverter circuit16is a circuit configured to convert a constant voltage into AC voltage, and is composed of an H-bridge circuit including an Insulated Gate Bipolar Transistor (IGBT). That is, the inverter circuit16includes four IGBTs18a,18b,18c, and18d. A positive voltage, that is, a constant voltage, is applied to the collectors of the IGBTs18aand18c, and a negative voltage, that is, a constant voltage, is applied to the emitters of the IGBTs18band18d. Each of the emitters of the IGBTs18aand18cis electrically connected to the collectors of the IGBTs18band18d. The inverter circuit16is operated to generate an AC voltage between the two emitters of the IGBTs18aand18cof a pair of output terminals when a clock signal is applied to the base of each of the IGBTs18a,18b,18c, and18d. Ends of the pair of inductor elements17aand17bare connected to the pair of output terminals of the inverter circuit16, and the other ends define the pair of output terminals13of the power supply boards10A,10B, and10C.

The synchronous circuit15is a circuit configured to generate four clock signals to control the operation of the inverter circuit16. The synchronous circuit15is configured so as to be able to set the generation operation of the clock signal into two types of a first operation and a second operation. Upon being set to the first operation, the synchronous circuit15generates the standard signal SYNC, that is, a clock signal obtained by frequency-dividing the operation clock generated by a built-in crystal oscillator. Then, on the basis of the generated standard signal SYNC, the synchronous circuit15generates control signals (clock signals) Va, Vb, Vc, and Vd to be applied to the base of the IGBTs18a,18b,18c, and18din the inverter circuit16, and applies the control signals Va, Vb, Vc, and Vd to the IGBTs18a,18b,18c, and18din the inverter circuit16. At the same time, the synchronous circuit15set to the first operation mode transmits the generated standard signal SYNC to the external power supply board10. On the other hand, upon being set to the second operation mode, the synchronous circuit15receives the standard signal SYNC transmitted from the external synchronous circuit15set to the first operation mode as a reference signal REF, adjusts the phase of the standard signal SYNC generated therein in the same manner as described above by comparing the phase of the standard signal SYNC with the phase of the reference signal REF. Then, the synchronous circuit15generates the control signals (clock signals) Va, Vb, Vc, and Vd on the basis of the standard signal SYNC the phase of which is adjusted, and applies the generated control signals Va, Vb, Vc, and Vd to the IGBTs18a,18b,18c, and18din the inverter circuit16. At the same time, the synchronous circuit15set to the second operation mode transmits the standard signal SYNC the phase of which is adjusted, to the external power supply board10.

In the contactless power feeding system100according to the present example embodiment, the synchronous circuit15of a one power supply board among the power supply boards10is set to the first operation mode in advance, and the synchronous circuit15of the remaining power supply boards excluding the one power supply board among the power supply boards10, is set to the second operation mode in advance. Then, the synchronous circuits15of the power supply boards10are configured to mutually transmit and receive the standard signal SYNC used to drive the inverter circuit16.

The power distribution circuit11includes a plurality of resonance circuits19the number of which corresponds to the number of the power supply lines12, and a connection circuit20for electrically connecting the resonance circuit19to the power supply boards10. The connection circuit20is configured to connect respective pairs of input terminals of the resonance circuits19to the respective pairs of output terminals13of the power supply boards10in an alternating manner in parallel via capacitors22. Each of the resonance circuits19includes a pair of input terminals21and a pair of output terminals23connected to each of the power supply lines12, and generates AC power by causing the AC voltage applied to the pair of input terminals to resonate, and outputs the generated AC power to each of the power supply lines12. With the power distribution circuit11of such a configuration, the AC power generated by each of the power supply boards10is distributed to the power supply lines12, and the distributed AC power is combined for each of the power supply lines12and is supplied toward each of the power supply lines12.

Next, an example of waveforms of various s signals generated by the power supply board10will be illustrated. FIG.4illustrates an example of waveforms when the power supply board10is set to the second operation mode.

The power supply board10set to the second operation mode performs a phase comparison between the reference signal REF received from the external power supply board10set to the first operation mode and the standard signal SYNC generated therein, and adjusts the phase of the standard signal SYNC on the basis of the comparison results. Then, the power supply board10set to the second operation mode generates four control signals Va, Vb, Vc, and Vd to synchronize with the standard signal SYNC the phase of which is adjusted. Then, by driving the inverter circuit16on the basis of the control signals Va, Vb, Vc, and Vd, the power supply board10causes the inverter circuit16to output AC voltage Vu-Vv. The AC voltage Vu−Vv output from the power supply board10is converted into an AC voltage VOUT with an AC waveform that changes smoothly, by passing through the power distribution circuit11. The AC voltage VOUT is then supplied to the power supply line12.

To prevent a flow-through current from occurring in the inverter circuit16, the power supply board10generates the four control signals Va, Vb, Vc, and Vd such that the control signals Va and Vd and the control signals Vb and Vc alternately become high level by synchronizing with the standard signal SYNC, while providing a pause period between the ON period of the control signal Va and the ON period of the control signal Vb, and between the ON period of the control signal Vc and the ON period of the control signal Vd. In this process, to reduce or prevent a back electromotive force of an inductor on the output side of the inverter circuit16, the power supply board10generates the four control signals Va, Vb, Vc, and Vd to provide an overlapping period during which the control signal Va and the control signal Vc are turned ON at the same time, and an overlapping period during which the control signal Vb and the control signal Vd are turned ON at the same time.

Next, with reference toFIG.5toFIG.7, the details of the configuration of the synchronous circuit15of the power supply board10will be described.FIG.5is a block diagram illustrating a detailed functional configuration of the synchronous circuit15.FIG.6is a block diagram illustrating a hardware configuration for implementing the synchronous circuit15.FIG.7is a diagram illustrating a connection configuration between the synchronous circuits15of the power supply boards10.FIGS.5to7illustrate configuration examples when the number of the power supply boards10of the contactless power feeding system100is four, for example.

As illustrated inFIG.5, as functional components, the synchronous circuit15includes an oscillator24, a selector25, a driver26, and three synchronization signal generation units301,302, and303including a selector27, a synchronizer28, and a variable delay element29. The synchronous circuit15is provided with the synchronization signal generation units301,302, and303, the number obtained by subtracting one from the total number of the power supply boards10. In this example, one of four identifier IDs “0”, “1”, “2”, and “3” is distributed and set in advance to each of the synchronous circuits15in the four power supply boards10. The synchronous circuit15set with the identifier ID “0” is configured to operate in the first operation mode, and the synchronous circuit15set with any one of the identifier IDs “1”, “2”, and “3” is configured to operate in the second operation mode. Moreover, each of the synchronous circuits15in the four power supply boards10is connected to the synchronous circuits15of the other three power supply boards10by a communication line in a communicable manner. The synchronous circuits15are configured to be able to mutually transmit and receive the standard signal SYNC generated by the synchronous circuits15of the four power supply boards10. In the following explanation, the standard signal SYNC transmitted from the power supply board10to which the identifier ID “0” is set in advance is referred to as a reference signal REF0, the standard signal SYNC transmitted from the power supply board10to which the identifier ID “1” is set in advance is referred to as a reference signal REF1, the standard signal SYNC transmitted from the power supply board10to which the identifier ID “2” is set in advance is referred to as a reference signal REF2, and the standard signal SYNC transmitted from the power supply board10to which the identifier ID “3” is set in advance is referred to as a reference signal REF3.

A crystal oscillator, a PLL, a frequency divider, and the like are built into the oscillator24. The oscillator24generates the standard signal SYNC, that is, a clock signal, by frequency-dividing the operation clock generated by the crystal oscillator. For example, the operation clock is set to about 20 MHz, and the standard signal SYNC is set to about 8.9 kHz, for example.

The functions of the selector27, the synchronizer28, and the variable delay element29of the synchronization signal generation units301,302, and303will be described. The selector27selects one of the two reference signals REF transmitted from two of the other three power supply boards10, and inputs the selected reference signal REF to the synchronizer28. The variable delay element29receives the standard signal SYNC generated by the oscillator24or the standard signal SYNC the phase of which is adjusted by the synchronizer28, samples the received standard signal SYNC therein, causes the sampled standard signal SYNC to delay by the delay time corresponding to the transmission delay of the reference signal REF selected by the selector27, and inputs the delayed standard signal SYNC to the synchronizer28. The synchronizer28compares the phase of the reference signal REF selected by the selector27with the phase of the standard signal SYNC input from the variable delay element29. If the phase delay of the standard signal SYNC is detected, the synchronizer28adjusts the standard signal SYNC such that the cycle of the standard signal SYNC generated by the oscillator24is gradually shortened (varied). On contrary, if the phase advance of the standard signal SYNC is detected by phase comparison, the synchronizer28adjusts the standard signal SYNC such that the cycle of the standard signal SYNC generated by the oscillator24is gradually extended (varied). In this process, delay occurs in a phase adjustment process of the standard signal SYNC. Hence, a conflict may occur between the detection of phase delay and the detection of phase advance. In this case, the synchronizer28does not perform the phase adjustment process. Moreover, the synchronizer28performs the adjustment process only when a phase difference within a predetermined range is detected. When a phase difference exceeding the predetermined range is detected, or when the transition of the level of reference signal REF cannot be detected within one cycle of the standard signal SYNC, the synchronizer28detects that a loss of synchronization (synchronization abnormality) of the reference signal REF has occurred.

The three synchronization signal generation units301,302, and303operate the selector27to select one signal from the three reference signals REF received from the external power supply board10among the four reference signals REF0to REF3. Moreover, when the synchronous circuit15is set to the first operation mode, the synchronizer28of the three synchronization signal generation units301,302, and303only detects the loss of synchronization of the reference signal REF generated by the external synchronous circuit15with respect to the standard signal SYNC. On the other hand, when the synchronous circuit15is set to the second operation mode, the synchronizer28to which the reference signal REF from the external synchronous circuit15operating in the first operation mode is selectively input, performs phase comparison and phase adjustment on the standard signal SYNC as described above, and the other two synchronizers28only detect the loss of synchronization of the reference signal REF with respect to the standard signal SYNC.

The selector25selects one signal from the standard signal SYNC generated by the oscillator24and the standard signals SYNC adjusted by the three synchronizers28, and inputs the selected standard signal SYNC to the driver26. That is, when the synchronous circuit15is set to the first operation mode, the selector25selects the standard signal SYNC from the oscillator24. On the other hand, when the synchronous circuit15is set to the second operation mode, the selector25selects the standard signal SYNC from the synchronizer28that performs phase adjustment on the standard signal SYNC among the three synchronizers28.

Upon receiving the standard signal SYNC selectively output by the selector25, the driver26generates the control signals Va, Vb, Vc, and Vd to drive the inverter circuit16to synchronize with the standard signal SYNC, and applies the control signals Va, Vb, Vc, and Vd to the inverter circuit16. According to such a configuration, it is possible to drive the inverter circuit16such that the phases of the AC powers output to the respective power supply lines12from the inverter circuits16of the four power supply boards10match with each other.

As illustrated inFIG.5, the synchronous circuit15includes signal ports for four reference signals REF0to REF3. In the synchronous circuit15, by validating any one of setting signals EN0to EN3according to the identifier ID set to the power supply board10, only one of the signals ports for the four reference signals REF0to REF3is switched to the output port for the standard signal SYNC, and the other ports are set as the input ports for the reference signal REF from the external power supply board10. Consequently, the standard signal SYNC is output to the one signal port selected from the four signal ports.

As illustrated inFIG.6, the synchronous circuit15is implemented by a Micro Controller Unit (MCU)41that is a computer system built on an integrated circuit, and a Field Programmable Gate Array (FPGA)42that is a device in which programmable gates are integrated. The FPGA42contains Universal Asynchronous Receiver/Transmitters (UARTs)43aand43bthat are communication devices configured to implement the communication between the power supply boards10using the asynchronous half-duplex communication method. The UARTs43aand43bhave a duplex structure with a communication line and a connector configured to connect the power supply boards10. In the FPGA42, the circuit units illustrated inFIG.5are built. If the MCU41has sufficient processing power, the function of the synchronous circuit15may be functionally provided by the MCU41. Moreover, the UARTs43aand43bmay be built into the MCU41.

With reference toFIG.7, the connection configuration between the synchronous circuits15in the four power supply boards10of the contactless power feeding system100will be described. The synchronous circuit15in the four power supply boards10is configured to be able to transmit and receive the standard signal SYNC, a command signal CMD, and a response signal RSP via a transmission line used for inter-board communication. In this example, the transmission line used for inter-board communication is duplexed with a communication device, a communication line, and a connector. That is, the FPGA42of one of the power supply boards10to which the identifier ID “0” is set in advance, transmits the standard signal SYNC generated by the internal oscillator24as the reference signal REF0, to the FPGAs42of the other three power supply boards10. On the other hand, the FPGAs42of the three power supply boards10to which the identifier IDs “1”, “2”, and “3” are set in advance, each transmit the standard signal the phase of which is adjusted on the basis of the reference signal REF0, to the FPGAs42of the other three power supply boards10as the reference signals REF1, REF2, and REF3. The MCUs41of the four power supply boards10mutually transmit and receive the command signal CMD and the response signal RSP, by specifying the identifier ID of the power supply board10of the transmission destination.

With reference toFIG.8, the functional configuration of the MCU41in the synchronous circuit15will be described. As functional components, the MCU41includes an abnormality detector51, a change controller52, and a delay calculator53.

The abnormality detector51determines an abnormality of each of the power supply boards10on the basis of the conditions of the standard signal SYNC generated by the power supply board10and the reference signal REF received from another power supply board10except the power supply board10. For example, if the synchronous circuit15detects a synchronization abnormality of the reference signal REF, the abnormality detector51determines that a synchronization abnormality has occurred in another power supply board10corresponding to the reference signal REF. In this case, the abnormality detector51exchanges the determination results of a synchronization abnormality relating to the power supply boards10, with the power supply boards10using the command signal CMD and the response signal RSP. Then, the abnormality detector51determines the consistency of the determination results among the power supply boards10, and specifies whether there is a failure in each of the power supply boards10on the basis of the determination results. For example, the abnormality detector51specifies a failure in the circuit or the transmission line of a certain power supply board10on the basis of a mismatch with the determination results of a synchronization abnormality of the other power supply boards10. Moreover, when the power supply boards10simultaneously determine that there is a synchronization abnormality in the power supply board10, the abnormality detector51specifies that there is a failure in the circuit or the transmission line of the power supply board10.

Moreover, the abnormality detector51is operable to determine an abnormality of the power supply boards10on the basis of the communication conditions of the command signal CMD and the response signal RSP transmitted and received to and from the power supply boards10as heartbeat commands. Specifically, the abnormality detector51of the synchronous circuit15set to the first operation mode, periodically transmits the command signal CMD to another power supply board10, and the abnormality detector51of the synchronous circuit15in the other power supply board10sends back the response signal RSP in response. Then, the abnormality detector51of the synchronous circuit15set to the first operation mode specifies an abnormality of the other power supply board10set to the second operation mode on the basis of the reception condition of the response signal RSP. In this process, the abnormality detector51may also specify an abnormality of the power supply boards10including the power supply board10, in combination with the determination results of the synchronization abnormality of the power supply board10described above.

Moreover, the abnormality detector51is operable to determine a failure of the inverter circuit16in the power supply board10, by monitoring the output current of the inverter circuit16.

The change controller52is configured or programmed to change the operation mode of the power supply boards10on the basis of the abnormality specification results by the abnormality detector51. Specifically, when an abnormality of the power supply board10is determined, and when the power supply board10is set to the first operation mode, the change controller52stops outputting the standard signal SYNC and the reference signal REF, and stops supplying AC power. The change controller52then transmits, to another power supply board10, the command signal CMD to change one of the other power supply boards10to the first operation mode, by broadcasting. Upon receiving the command signal CMD, the change controller52of the other power supply board10controls to change the synchronization process to the first operation mode, or to change the reference signal REF of the synchronization destination in the second operation mode. Moreover, when an abnormality of the power supply board10is determined, and when the power supply board10is set to the second operation mode, the change controller52stops outputting the standard signal SYNC and the reference signal REF, and stops supplying AC power.

Furthermore, when an abnormality of the other power supply board10is determined, the other power supply board10is set to the first operation mode, and the power supply board10should be set to the first operation mode next, the change controller52transmits the command signal CMD to change the operation mode to the other power supply board10by broadcasting, and controls to change the power supply board10to the first operation mode. Upon receiving the command signal CMD, the other power supply board10controls to change the synchronization destination in the second operation mode, and the power supply board10that has been operating in the first operation mode stops supplying power. Still furthermore, when an abnormality of the other power supply board10is determined, and the concerned power supply board10is set to the second operation mode, the change controller52transmits the command signal CMD to provide a notification of a detection of abnormality, to that power supply board10. Upon receiving the command signal CMD, the power supply board10stops outputting the standard signal SYNC and the reference signal REF, and stops supplying AC power.

The delay calculator53measures the transmission delay of the standard signal SYNC between the power supply boards10, and on the basis of the measured results, sets the delay time by a plurality of the variable delay elements29in the synchronous circuit15to be variable. Specifically, as an initialization process at the time of starting the contactless power feeding system100, the delay calculator53transmits the reference signal REF from the power supply board10to another power supply board10, measures the delay time of the reference signal REF sent back from the other power supply board10, and calculates the half value of the delay time as the transmission delay time (latency) between the power supply board10and the other power supply board10. The delay calculator53repeats such measurement to calculate the latency between the power supply board10and the other power supply board10, and on the basis of the latency value (calibration value), sets the delay time of the variable delay element29used for phase comparison of the reference signals REF from the respective other power supply boards10. Each of the delay calculators53of the power supply boards10performs the setting process of the delay time described above at the initialization process.

FIG.9is a timing chart for explaining the operation of phase comparison in the synchronous circuit15of the power supply board10. Thus, in the synchronous circuit15of the power supply board10, the reference signal REF2that is delayed from the signal REF1having delayed from the reference signal REF by the path delay including the propagation delay in the transceiver IC built into the power supply boards10and the transmission delay in the transmission line used for inter-board communication, by sampling latency in the synchronous circuit15, is received from the other power supply board10. After adjusting the standard signal SYNC generated therein or the phase of which is adjusted, to a standard signal SYNC1by delaying the standard signal SYNC by a time corresponding to the calibration value calculated by the delay calculator53, the synchronous circuit15can perform a phase comparison between the standard signal SYNC1and the reference signal REF2.

FIGS.10A and10Bare timing chart for explaining the operation of phase adjustment of the standard signal SYNC in the synchronous circuit15of the power supply board10operating in the second operation mode.FIG.10Ais a timing chart when the delay of the standard signal SYNC1is detected.FIG.10Bis a timing chart when the advance of the standard signal SYNC1is detected. Thus, when the phase delay of the standard signal SYNC1to which the delay time is added with respect to the reference signal REF from the power supply board10operating in the first mode is detected, the synchronous circuit15controls the oscillator24such that the cycle of the standard signal SYNC is gradually shortened. On the other hand, when the phase advance of the standard signal SYNC1to which the delay time is added with respect to the reference signal REF from the power supply board10operating in the first operation mode is detected, the synchronous circuit15controls the oscillator24such that the cycle of the standard signal SYNC is gradually extended. Consequently, the synchronous circuit15can adjust the phase of the standard signal SYNC such that the phase of the standard signal SYNC matches the phase of the reference signal REF prior to the occurrence of a path delay.

Next, the procedure of a contactless power feeding method using the contactless power feeding system100according to the present example embodiment will be described.

Upon activation of the power supply board10that is any one of the power supply boards10of the contactless power feeding system100, the command signal CMD to instruct activation is transmitted from the power supply board10to another power supply board10. Consequently, a synchronous processing mode is set in the synchronous circuit15in each of the power supply boards10.

Then, the synchronous circuit15of the one power supply board10set to the first operation mode among the power supply boards10drives the inverter circuit16of the one power supply board10on the basis of the standard signal SYNC generated by the internal oscillator24. Then, the one power supply board10starts supplying AC power to the power supply lines12. At the same time, the standard signal SYNC is transmitted as the reference signal REF, from the synchronous circuit15of the one power supply board10set to the first operation mode, to the remaining power supply boards10other than the one power supply board10.

In contrast, the synchronous circuit15of the remaining power supply boards10other than the one power supply board10performs a phase comparison between the standard signal SYNC generated by the internal oscillator24and the reference signal REF transmitted from the one power supply board10, to adjust the phase of the standard signal SYNC. Then, the synchronous circuit15of the remaining power supply boards10drives the inverter circuit16of the remaining power supply boards10on the basis of the standard signal SYNC the phase of which is adjusted, and the remaining power supply boards10start supplying AC power to the power supply lines12.

The advantageous effects obtained by the contactless power feeding system100of the present example embodiment described above, and the contactless power feeding method using the contactless power feeding system100will now be described.

According to the present example embodiment, the AC power generated by the power supply boards10is distributed and supplied to the power supply lines12. Hence, it is possible to supply power to the mobile body130from the power supply lines12in a contactless manner. Consequently, even if the power supply from the power supply board10is stopped due to a failure or the like, it is possible to supply power to the mobile body130from the remaining power supply boards10other than the power supply board10via the power supply lines12. Hence, it is possible to stably supply power to the mobile body130.

In the present example embodiment, in the one power supply board10set to the first operation mode in advance, AC power is generated on the basis of the standard signal SYNC generated therein, and in the remaining power supply boards10set to the second operation mode in advance, AC power the phase of which matches that of the AC power generated by the one power supply board10is generated on the basis of the standard signal SYNC generated therein and the reference signal REF generated by the one power supply board10. Consequently, it is possible to align the phases of the AC powers supplied to the power supply lines12from the power supply boards10, and efficiently supply power to the mobile body130from the power supply boards10.

Moreover, in the present example embodiment, the remaining power supply boards10drive the inverter circuit16by changing the cycle of the standard signal SYNC on the basis of the comparison results of the phases of the reference signal REF received from the one power supply board10and the standard signal SYNC generated therein. According to such a configuration, it is possible to efficiently adjust the phase of the standard signal SYNC of the remaining power supply boards10, and efficiently perform the process of adjusting the phase of the AC power generated by the remaining power supply boards10with respect to the phase of the AC power generated by the one power supply board10.

Furthermore, in the present example embodiment, the power supply boards10are configured to be able to mutually transmit and receive the standard signal SYNC generated therein, and each of the power supply boards10is configured to determine an abnormality of another power supply board10on the basis of the standard signal SYNC received from the other power supply board10except the power supply board10. In this case, the power supply boards10can efficiently detect the abnormality of the other power supply board10.

Still furthermore, in the present example embodiment, when an abnormality of the one power supply board10set to the first operation mode is determined, the power supply boards10operate to change the power supply board10set to the first operation mode. According to such a configuration, it is possible to stably perform the process of adjusting the phase of AC power among the power supply boards10, and stably supply power to the mobile body130without fail.

Still furthermore, in the present example embodiment, the power supply boards10operate to determine an abnormality on the basis of at least one of the conditions of the reference signal REF and the communication conditions with another power supply board10. In this case, it is possible to efficiently determine the abnormality of the other power supply board10.

Still furthermore, in the present example embodiment, the power supply boards10are operable to measure the transmission delay of the reference signal REF between the power supply board10and another power supply board10, and operable to set the calibration value to control the phase of AC power on the basis of the transmission delay. Such a configuration allows to adjust the phase of AC power while taking into account the transmission delay among the power supply boards10, and to more stably supply power to the mobile body130.

Still furthermore, in the present example embodiment, on the basis of the comparison results between the phase of the reference signal REF and the phase of the standard signal SYNC delayed according to the calibration value, the power supply boards10drive the inverter circuit16such that the phases of the AC powers match with each other. In this case, by comparing the phases of the standard signal SYNC while taking into account the transmission delay among the power supply boards10, it is possible to adjust the phase of AC power in a more significant manner.

While the principles of the present disclosure have been illustrated and described in the example embodiments, it will be appreciated by those skilled in the art that the present disclosure can be modified in arrangement and detail without departing from such principles. The present disclosure is not limited to the specific configurations disclosed in the present example embodiments. We therefore claim all modifications and changes that come within the scope and spirit of the following claims.

In the contactless power feeding apparatuses according to the example embodiments described above, it is preferable that the power supply boards each include an inverter circuit, and cause the inverter circuit to generate AC power; the one power supply board that is any one of the power supply boards is set to the first operation mode in advance, and the remaining power supply boards excluding the one power supply board among the power supply boards are set to the second operation mode in advance; based on a clock signal generated therein, the one power supply board operates to drive the inverter circuit of the one power supply board and to transmit the clock signal as a standard signal to the remaining power supply boards; and, based on a clock signal generated therein and the standard signal received from the one power supply board, the remaining power supply boards operate to drive the inverter circuit such that the phase of the AC power output from the one power supply board matches the phase of the AC power output from the remaining power supply boards.

In this case, in the one power supply board set to the first operation in advance, the AC power is generated on the basis of the clock signal, and in the remaining power supply boards set to the second operation mode in advance, the AC power the phase of which matches that of the AC power generated by the one power supply board is generated on the basis of the clock signal and the clock signal in the one power supply board. Consequently, it is possible to align the phases of the AC power supplied to the power supply lines from the power supply boards, and efficiently supply power to the mobile body from the power supply boards.

Moreover, in the contactless power feeding apparatuses according to the example embodiments described above, it is preferable that the remaining power supply boards drive the inverter circuit such that the phases of the AC power match with each other by changing the cycle of the clock signal on the basis of the comparison results of the phases of the standard signal received from the one power supply board and the clock signal generated therein. According to such a configuration, it is possible to efficiently adjust the phase of the clock signal in the remaining power supply boards, and efficiently perform the process of adjusting the phase of the AC power generated by the remaining power supply boards, with respect to the phase of the AC power generated by the one power supply board.

Furthermore, in the contactless power feeding apparatuses according to the example embodiments described above, it is preferable that the power supply boards are configured to be able to mutually transmit and receive the clock signal generated therein as a standard signal, and that each of the power supply boards includes the abnormality detector configured to determine, on the basis of the standard signal received from another power supply board except the one power supply board, an abnormality of the other power supply board. In this case, the power supply boards can efficiently detect the abnormality of the other power supply board.

Still furthermore, in the contactless power feeding apparatuses according to the example embodiments described above, it is preferable that the power supply boards further include the change controller configured or programmed to change the power supply board set to the first operation mode when the abnormality detector determines an abnormality of the one power supply board. According to such a configuration, it is possible to stably perform the process of adjusting the phase of AC power among the power supply boards, and stably supply power to the mobile body without fail.

Still furthermore, in the contactless power feeding apparatuses according to the example embodiments described above, it is preferable that the abnormality detector determines an abnormality on the basis of at least one of the conditions of the standard signal and the communication conditions with the other power supply board. In this case, it is possible to efficiently determine the abnormality of the other power supply board.

Still furthermore, in the contactless power feeding apparatuses according to the example embodiments described above, it is preferable that the power supply boards include the delay calculator configured to measure the transmission delay of the standard signal between the one power supply board and another power supply board, and set the calibration value to control the phase of the AC power on the basis of the transmission delay. Such a configuration allows to adjust the phase of AC power while taking into account the transmission delay among the power supply boards, and to further stably supply power to the mobile body.

Still furthermore, in the contactless power feeding apparatuses according to the example embodiments described above, it is preferable that, on the basis of the comparison results between the phase of the standard signal and the phase of the clock signal delayed according to the calibration value, the power supply boards drive the inverter circuit such that the phases of the AC power match with each other. In this case, by comparing the phases of the clock signal while taking into account the transmission delay among the power supply boards, it is possible to adjust the phase of AC power in a more significant manner.