JP7518674B2 - Contactless Power Supply System - Google Patents

Description

The present invention relates to a contactless power supply system capable of contactlessly supplying power to a mobile object stopped in a stopping range for charging .

One example of a contactless power supply system capable of supplying a predetermined amount of power to a moving object without electrical contact is the "contactless power transmission system" disclosed in Patent Document 1 below. This system is composed of a power transmitting device and a power receiving device, and charges a capacitor provided in an automated guided vehicle (moving object) by supplying power contactlessly. The power transmitting device includes a high-frequency power supply device that outputs high-frequency power, a power transmitting coil connected to the high-frequency power supply device, and a communication circuit for communication, and the power receiving device includes a power receiving coil magnetically coupled to the power transmitting coil, a communication circuit for communication with the communication circuit, and a power transmission start switch for outputting a power transmission start signal.

As a result, when an operator operates the power transmission start switch of the power receiving device, a power transmission start signal is input to the power transmitting device via the communication circuits of the power receiving side and the power transmitting side, and the high frequency power supply device is started, making it possible to start power transmission without providing a power transmission start switch on the power transmitting device. Similarly, when power transmission is to be stopped, the operator operates the power transmission stop switch of the power receiving device, and a power transmission stop signal is input to the power transmitting device via the communication circuits of the power receiving side and the power transmitting side, stopping the high frequency power supply device. As a result, it is possible to stop power transmission without providing a power transmission stop switch on the power transmitting device.

JP 2017-195675 A

However, according to the technology disclosed in Patent Document 1, in order to start or stop power transmission to an automated guided vehicle, an operator must operate a power transmission start switch or power transmission stop switch on the power receiving device. Therefore, while an operator's manual labor is required to start or stop the supply of power to an automated guided vehicle, automated guided vehicles in operation are often moving in automatic driving. Therefore, there is a problem in terms of safety management that it is difficult for an operator to get into a moving automated guided vehicle to perform such operations.

As disclosed in the above-mentioned Patent Document 1, for example, an operation remote control having a power transmission start switch and a power transmission stop switch may be provided, and a separate communication circuit for communicating with the operation remote control may be provided in the power receiving device, and operation signals and the like may be sent and received via wireless communication between the operation remote control and the communication circuit (Patent Document 1; paragraph 0076). However, a system including such an operation remote control makes the overall system configuration complex, and when there are multiple unmanned guided vehicles (mobiles), it is necessary to identify the guided vehicle to be operated. This can result in a new problem that the system configuration and operation are easily complicated.

The present invention has been made to solve the above-mentioned problems, and aims to provide a non-contact power supply system that can safely and automatically supply a specified amount of power to a mobile object.

In order to achieve the above object, a contactless power supply system according to claim 1 of the claims includes a power receiving device provided in a mobile body that stops within a stop range for charging and receives a supply of power contactlessly , and a power transmitting device provided in the stop range of the mobile body and transmits power to the power receiving device, the power receiving device includes a power receiving unit capable of receiving transmitted power contactlessly, a transmitting unit capable of transmitting information via optical wireless communication, and a power receiving side control unit capable of controlling the power receiving unit and the transmitting unit, the power transmitting device includes a power transmitting unit capable of transmitting the power contactlessly to the power receiving unit, a receiving unit capable of receiving the information from the transmitting unit via optical wireless communication, and a power transmitting unit capable of transmitting the power contactlessly to the power receiving unit. and a power transmitting side control unit capable of controlling the power receiving unit and the receiving unit, wherein the power receiving side control unit controls the transmitting unit to repeatedly transmit identification information capable of identifying the power receiving device or the moving body and power transmission request information requesting the transmission of power sufficiently smaller than a specified power of normal power transmission before the moving body stops in the stop range , and when the receiving unit receives the identification information and the power transmission request information, the power transmitting side control unit controls the power transmitting unit to start backup power transmission that sends power sufficiently smaller than the specified power before performing normal power transmission based on the normal power transmission request information requesting the transmission of the specified power.

In the contactless power supply system according to claim 1, a power receiving side control unit of the power receiving device controls a transmission unit to repeatedly transmit, via the transmission unit, identification information capable of identifying the power receiving device or the mobile body and power transmission request information requesting the transmission of power sufficiently smaller than a predetermined power of normal power transmission, before the mobile body stops in a stop range . In response to this, a power transmitting side control unit of the power transmitting device controls, when the receiving unit receives the identification information and the power transmission request information, the power transmitting unit to start backup power transmission that transmits power sufficiently smaller than the predetermined power before normal power transmission is performed based on the normal power transmission request information requesting the transmission of the predetermined power.

The transmitting unit of the power receiving device transmits information to the receiving unit of the power transmitting device by optical wireless communication. The optical wireless communication is, for example, infrared communication, and the emitted light of the optical wireless communication has a sharper directivity than that of radio waves due to the characteristics of an infrared emitting module having a light collecting unit such as a lens, although it depends on the type of the radio wave transmitting antenna. Since the transmitting unit of the power receiving device repeatedly transmits the identification information and the power transmission request information before the moving body stops in the stopping range , when the receiving unit of the power transmitting device receives the identification information and the power transmission request information, it is highly likely that the moving body equipped with the transmitting unit is present or stopped in the stopping range . Therefore, in such a case, the power transmitting unit of the power transmitting device starts backup power transmission in which a power sufficiently smaller than the predetermined power during normal power transmission is supplied. As a result, when the moving body is present (stopped) in the stopping range , the power transmitting device automatically starts backup power transmission prior to normal power transmission, so that, for example, even if the moving body stops slightly out of the stopping range , it is unlikely that the power transmitting device will break down or that electromagnetic waves generated by the power transmission will have a physical adverse effect on the worker.

Furthermore, the contactless power supply system described in claim 2 of the claims has a technical feature in that, in the contactless power supply system described in claim 1, the receiving side control unit controls the transmitting unit to transmit the normal power transmission request information via the transmitting unit when the power received by the backup power transmission is a predetermined value, and the transmitting side control unit controls the power transmitting unit to start the normal power transmission when the receiving unit receives the normal power transmission request information.

In the contactless power supply system according to claim 2, the power receiving side control unit controls the power transmitting unit to transmit normal power transmission request information via the power transmitting unit when the power received by the backup power transmission is a predetermined value. Also, the power transmitting side control unit controls the power transmitting unit to start normal power transmission when the receiving unit receives the normal power transmission request information. When the received power is lower than the predetermined value, for example, the mobile object may be located (or stopped) slightly out of the stop range , or the power transmitting unit or the power receiving unit may be broken. Also, when the received power is higher than the predetermined value, for example, the power transmitting unit may be broken. As a result, when the power received by the backup power transmission is not a predetermined value, the normal power transmission request information is not transmitted, so that it is possible to avoid starting normal power transmission when the mobile object is located (or stopped) slightly out of the stop range , or when the power transmitting device or the power receiving device may be broken. Therefore, a specified amount of power through normal power transmission is supplied to the moving body only when the moving body is properly present (or stopped) within the stopping range or when both the power transmitting device and the power receiving device are normal, thereby further improving safety.

Furthermore, the contactless power supply system described in claim 3 of the claims has the technical feature that, in the contactless power supply system described in claim 1 or 2, the power receiving side control unit controls the transmission unit to repeatedly transmit the normal power transmission request information via the transmission unit at a predetermined timing during a period in which the power receiving unit is receiving the predetermined power, and the power transmitting side control unit controls the power transmitting unit to stop the normal power transmission if the receiving unit does not receive the normal power transmission request information within a predetermined period that includes multiple predetermined timings.

In the contactless power supply system according to claim 3, the power receiving side control unit controls the power transmitting unit to repeatedly transmit normal power transmission request information via the power transmitting unit at a predetermined timing during a period in which the power receiving unit receives a predetermined power. In addition, the power transmitting side control unit controls the power transmitting unit to stop normal power transmission if the receiving unit does not receive the normal power transmission request information within a predetermined period including a plurality of predetermined timings. As a result, even if the transmitting unit of the power receiving device repeatedly transmits normal power transmission request information at a predetermined timing, for example, if the mobile object moves and leaves the stop range during the reception of the predetermined power, or if the power receiving unit of the power receiving device breaks down, the receiving unit of the power transmitting device will not be able to receive the normal power transmission request information within the predetermined period, so that the power transmitting device can automatically stop normal power transmission. Therefore, the predetermined power by normal power transmission continues to be supplied to the mobile object only when the mobile object is appropriately present (or stopped) within the stop range or the power receiving device is normal, so that safety can be further improved.

The contactless power supply system described in claim 4 of the claims has the technical feature that, in the contactless power supply system described in any one of claims 1 to 3, the power receiving device includes a receiving unit capable of receiving information via optical wireless communication in addition to the transmitting unit, the power transmitting device includes a transmitting unit capable of transmitting information via optical wireless communication in addition to the receiving unit, and the power transmitting side control unit transmits the identification information or information related to the identification information received by the receiving unit of the power transmitting device to the receiving unit of the power receiving device via the transmitting unit of the power transmitting device, and conveys it to the power receiving side control unit.

In the contactless power supply system described in claim 4, the power transmission side control unit transmits the identification information or information related to the identification information received by the receiving unit of the power transmission device to the receiving unit of the power receiving device via the transmitting unit of the power transmission device, and conveys it to the power receiving side control unit. This allows the power receiving device to confirm that the power transmission device has received the identification information transmitted by the power receiving device and recognized the power receiving device, and that pairing in the communication procedure has been established with the power transmission device.

The contactless power supply system described in claim 5 of the claims has the technical feature that, in the contactless power supply system described in any one of claims 1 to 4, the power receiving device and the power transmitting device each have a wireless unit capable of wirelessly communicating with each other at close ranges, and the power transmitting side control unit transmits the identification information or information related to the identification information received by the receiving unit of the power transmitting device to the wireless unit of the power receiving device via the wireless unit of the power transmitting device, and conveys it to the power receiving side control unit.

In the contactless power supply system described in claim 5, the power receiving device and the power transmitting device each have a wireless unit capable of wireless communication with each other at a short distance. The power transmitting side control unit transmits the identification information or information related to the identification information received by the receiving unit of the power transmitting device to the wireless unit of the power receiving device via the wireless unit of the power transmitting device, and transmits it to the power receiving side control unit. This wireless communication uses radio waves as an information transmission medium, and although the radio waves depend on the type of transmitting antenna, they are generally less directional and more likely to reach a wide range than optical wireless communication that uses the emitted light of an optical module having a focusing unit such as a lens as a medium. As a result, for example, even in an environment where optical wireless communication is difficult to transmit to the receiving unit of the power receiving device, by using radio waves as an information transmission medium, the power receiving device can confirm that the power transmitting device has received the identification information transmitted by the power receiving device and recognized the power receiving device, and that pairing has been established with the power transmitting device in the communication procedure.

In the present invention, when a moving object is present (or stopped) within the stopping range , the power transmission device automatically starts backup power transmission prior to normal power transmission. In backup power transmission, power that is sufficiently smaller than the specified power during normal power transmission is supplied, so that even if the moving object is present (or stopped) slightly outside the stopping range , for example, it is unlikely that the power transmission device will break down or that electromagnetic waves generated during power transmission will have a physical adverse effect on workers. Therefore, the specified power can be safely and automatically supplied to the moving object.

1 is an explanatory diagram showing an example of the configuration of a charging system for an automatic guided vehicle, which is an embodiment of a non-contact power supply system of the present invention. FIG. 2(A) is a block diagram of a power transmitting device constituting the present charging system, and FIG. 2(B) is a block diagram of a power receiving device. 4 is a flowchart showing a flow of a power transmission control process executed by a power transmitting device of the present charging system. 4 is a flowchart showing a flow of a power reception control process executed by a power receiving device of the present charging system. FIG. 2 is a sequence diagram showing a series of flow of each process executed by the charging system from before charging of an automatic guided vehicle is started to before charging is completed, and shows an example under normal circumstances. FIG. 11 is a sequence diagram showing a series of processes executed by the charging system before charging of an automated guided vehicle is started and during charging, and shows an example of an abnormal termination due to the unmanned guided vehicle leaving the charging system. 7A is a block diagram of a power transmitting device and FIG. 7B is a block diagram of a power receiving device that constitute a charging system that is another embodiment of a contactless power supply system of the present invention.

Below, an example of the non-contact power supply system of the present invention applied to a charging system capable of charging a battery mounted on an automatic guided vehicle (AGV) will be described with reference to the drawings. Hereinafter, an automatic guided vehicle will be referred to as "AGV."

An AGV is an electric vehicle that runs on the power of a drive motor powered by power supplied from an on-board battery, and is a vehicle that drives autonomously along a pre-determined driving route (guideline) in a logistics warehouse, factory premises, etc., to transport cargo, etc. Such autonomous driving is typically performed by a drive controller installed in the AGV.

The AGV according to this embodiment is configured in a manner similar to known AGVs, including the overall vehicle structure, as well as the mechanisms and controls (control by a drive controller) related to driving, braking, and steering. The battery is configured as a battery pack in which multiple battery cells of a specific type, such as a lithium-ion secondary battery or a lead-acid battery, are connected in series. Therefore, please note that these will not be mentioned below unless specifically required.

As shown in FIG. 1, the charging system 10 of this embodiment can supply power to charge the batteries of such AGVs 100 at a charging station S. The charging system 10 is composed of, for example, a power transmission device 12 provided at the charging station S on a floor F on which multiple AGVs 100 can travel, and multiple power receiving devices 15 mounted on each of the AGVs 100.

In this embodiment, guidelines G that guide the driving route are displayed on the floor F, and the AGV 100 is controlled to travel along a predetermined route by, for example, having the drive controller recognize the guidelines G through image recognition. The charging station S in which the power transmission device 12 is provided is provided, for example, midway along the guidelines G (driving route).

In Fig. 1, the range (stop range) of the charging station S is indicated by a dashed line to clarify the planned position where the AGV 100 will stop when charging. Although not shown in Fig. 1, for example, a stop line that can be image-recognized by the drive controller at a fixed position within the charging station S is displayed on the floor F.

As shown in FIG. 2(A), the power transmission device 12 is mainly composed of a main unit 21 and a coil unit 31, and is provided in a charging station S. In this embodiment, since it is necessary to install the coil unit 31 in a position close to the underside of the AGV 100 body (e.g., an underpanel, etc.), the main unit 21 and the coil unit 31 are provided in separate housings. For example, the coil unit 31 has an outer shape formed in a thin box shape, and is embedded in the floor F of the charging station S so as not to interfere with the travel of the AGV 100. The two units 21, 31 are electrically connected by a cable 30.

The main unit 21 includes a rectifier unit 22, a voltage converter 23, an inverter 24, and a controller 26, and is provided at a location (for example, in an unillustrated control panel installed on floor F) away from the buried conveying path (travel route) in consideration of the safety of maintenance work, for example. The coil unit 31 includes a power transmission coil 25 and an infrared unit 27. Of these, the rectifier unit 22, the voltage converter 23, the inverter 24, and the power transmission coil 25 constitute the power transmission section 20, and this power transmission section 20 is controlled by the controller 26 that functions as a power transmission control section.

That is, the power transmission unit 20 and the controller 26 are configured so that the AC power (e.g., three-phase AC power or single-phase AC power) supplied from the AC power source 18 is converted to DC power by the rectifier unit 22, then the voltage is stepped down or stepped up to a predetermined voltage by the voltage converter 23, and the predetermined AC power obtained by the inverter 24 is then converted to AC power of a predetermined frequency, and the predetermined AC power obtained can be supplied to the power transmission coil 25 via the cable 30.

The voltage converter 23 and the inverter 24 are provided with sensors (not shown) capable of detecting their respective input voltages, input currents, output voltages, output currents, and internal temperatures, and the outputs of these sensors are connected to the controller 26. Therefore, the controller 26 performs on/off control (switching control) of the semiconductor switching elements that constitute the voltage converter 23 and the inverter 24 based on information such as the voltage, current, and temperature of the voltage converter 23 and the inverter 24 output from these sensors. In other words, the voltage converter 23, the inverter 24, and the controller 26 are configured so that the DC voltage output by the voltage converter 23 and the frequency of the AC power output by the inverter 24 can be controlled based on the switching control of the controller 26.

The rectifier unit 22 is, for example, a full-wave rectifier circuit made up of multiple silicon diodes corresponding to each phase of AC power. The voltage converter 23 is, for example, a voltage conversion circuit made up of semiconductor switching elements such as power MOSFETs and IGBTs, and inductors. The inverter 24 is, for example, a high-frequency power generation circuit made up of multiple power MOSFETs and IGBTs. The power transmission coil 25 is an inductor that can transmit AC power to the coil unit 61 of the power receiving device 15 in a predetermined manner. Examples of predetermined methods include a magnetic field resonance method and an electromagnetic induction method.

The controller 26 is a control device composed of an MPU, memory (DRAM, ROM), interface, etc., and in this embodiment is configured to be able to control the voltage converter 23, inverter 24, and infrared unit 27. It controls the switching of the semiconductor switching elements of the voltage converter 23 and inverter 24, and is configured to obtain predetermined information received by the infrared unit 27. The memory (ROM) of the controller 26 stores predetermined programs that enable the MPU to control the voltage converter 23, inverter 24, and infrared unit 27, as well as a power transmission control program that enables the MPU to execute the power transmission control process described below.

The infrared unit 27 is an optical wireless communication device capable of optical wireless data communication using infrared rays (infrared light), and is configured to be able to communicate information using a communication protocol that complies with the IrDA (Infrared Data Association) standard. In this embodiment, for example, it is an infrared data receiving device that has the function of receiving optical wireless data transmitted from the infrared unit 57 of the power receiving device 15 and decoding the received data in the form of a light intensity signal into digital data of an electrical signal and outputting it to the controller 26. Note that instead of the infrared unit 27 that is dedicated to receiving, an infrared unit 28 that can transmit and receive and has a transmitting function in addition to a receiving function may be used. The infrared units 27, 28 may also perform optical wireless data communication with the infrared unit 57, etc. using their own communication protocol.

As shown in FIG. 2(B), the power receiving device 15 mounted on the AGV 100 is mainly composed of a main unit 51 and a coil unit 61. In this embodiment, the main unit 51 is provided near the battery 110 mounted on the AGV 100 to reduce power transmission loss, and the coil unit 61 is provided on the underpanel of the AGV 100 so as to face the road surface (floor F) as close as possible, in order to efficiently receive AC power transmitted by magnetic field resonance and electromagnetic induction.

The main unit 51 includes a rectifier unit 52, a charging unit 53, and a controller 56, and is provided, for example, near a battery 110 that can supply drive power to the traveling motor of the AGV 100. In contrast, the coil unit 61, which is provided in a position close to the road surface, such as on the underpanel of the AGV 100, includes a power receiving coil 54 and an infrared unit 57. Of these, the rectifier unit 52, the charging unit 53, and the power receiving coil 54 constitute the power receiving section 50, which is controlled by a controller 56 that functions as a power receiving control section. The two units 51, 61 are electrically connected by a cable 60.

That is, the power receiving unit 50 and the controller 56 are configured so that the AC power received by the power receiving coil 54 is converted to DC power by the rectifier unit 52, and then converted to a voltage suitable for charging by the charging unit 53, and the charging power can be supplied to the battery 110. The charging unit 53 is provided with sensors (not shown) that can detect the input voltage, input current, output voltage, output current, and their respective internal temperatures, and the sensor outputs are connected to the controller 56. The battery 110 is also provided with a voltage sensor 113 that can detect the battery voltage, a current sensor 115 that can detect the battery current, and a temperature sensor (not shown) that can detect the cell temperature of the battery 110, and the sensor outputs are connected to the controller 56.

For this reason, the controller 56 controls the switching of the semiconductor switching elements that make up the charging unit 53 based on the voltage, current, and cell temperature information output from the voltage sensor 113 and current sensor 115. In other words, the charging unit 53 and the controller 56 are configured so that the charging power (charging voltage and charging current) output by the charging unit 53 can be controlled based on the switching control of the controller 56.

The rectifier unit 52 is, for example, a rectifier circuit made up of multiple silicon diodes. The charging unit 53 is, for example, a charging control circuit made up of semiconductor switching elements such as power MOSFETs and IGBTs, and inductors, and can convert the DC voltage input from the rectifier unit 52 into a voltage suitable for the battery 110 and output it to the battery 110, and also includes a trickle charging circuit and a float charging circuit (not shown). The receiving coil 54 is an inductor that can receive AC power from the coil unit 31 using the transmission method (magnetic field resonance method, electromagnetic induction method, etc.) of the power transmitting device 12.

Like controller 26, controller 56 is a control device composed of an MPU, memory, etc. In this embodiment, it is configured to be able to control charging unit 53 and infrared unit 57. It is configured to control the switching of the semiconductor switching element of charging unit 53, and to send predetermined information to infrared unit 57. The memory (ROM) of controller 56 stores predetermined programs that allow the MPU to control charging unit 53 and infrared unit 57, a battery monitoring program that monitors the voltage and current of battery 110, a power receiving control program that allows the MPU to execute the power receiving control process described below, etc.

The infrared unit 57 is an optical wireless communication device using infrared (infrared light) that is configured to communicate information using a communication protocol conforming to the IrDA standard, for example, in correspondence with the infrared units 27, 28 (hereinafter referred to as "infrared unit 27, etc.") of the power transmitting device 12. In this embodiment, it is an infrared data transmitting device that has the function of encoding transmission data in the form of an electric signal (digital data), such as an ID (identification information) to be sent to the power transmitting device 12, into a light intensity signal and transmitting it. As described below, the ID is an identifier uniquely assigned to each power receiving device 15, etc., so that the power receiving device 15 or AGV 100 can be identified. Note that instead of the infrared unit 57 dedicated to transmission, an infrared unit 58 capable of transmitting and receiving, which has a receiving function in addition to a transmitting function, may be used.

Next, the power transmission control process by the power transmitting device 12 and the power reception control process by the power receiving device 15 will be described with reference to Figs. 3 to 6. The power transmission control process is performed by the controller 26 of the power transmitting device 12 executing a power transmission control program. The power reception control process is performed by the controller 56 of the power receiving device 15 executing a power reception control program. First, the power transmission control process will be described with reference mainly to Fig. 3.

<Power transmission control process>
3, when the power source of the power transmitting device 12 is turned on, the controller 26 of the main unit 21 starts the execution of a power transmission control program, and the power transmission control process starts. The power transmission control process starts with a predetermined initialization process in step S101. In this process, for example, the work area and flags of the memory of the controller 26 are cleared, and control commands for initial setting are sent to the voltage converter 23, the inverter 24, the infrared unit 27, etc.

Next, in step S103, a received information acquisition process is performed. Here, for example, a process is performed to read out the receive buffer in which the information received by the infrared unit 27 or the like is held. If the infrared unit 27 or the like has a memory, the receive buffer is secured in that memory, and if such a memory is not provided, the receive buffer is secured in the memory of the controller 26. For example, the controller 26 clears the receive buffer to zero so that it is empty after reading out the information received by the infrared unit 27 or the like.

In the next step S105, a process is performed to determine whether the infrared unit 27 etc. has received a backup power transmission command or the like. If it is determined that the received information is not a backup power transmission command or the like (S105; No), the process returns to step S103 again to perform the received information acquisition process. A backup power transmission command or the like is information transmitted by the power receiving device 15 of the AGV 100 requesting the power transmitting device 12 to supply power via the infrared units 57, 58, and includes, for example, a backup power transmission command (power transmission request information) and an ID that can identify the power receiving device 15 or AGV 100 that sent it. Note that when the communication protocol specifies that "the power receiving device 15 transmits only its ID when requesting the power transmitting device 12 to supply power," the backup power transmission command (power transmission request information) is unnecessary, and the power receiving device 15 transmits only its own ID to the power transmitting device 12.

As described below, when the controller 56 of the power receiving device 15 of the AGV 100 traveling along the guideline G determines that charging of the battery 110 is necessary, the controller 56 sends an instruction to the drive controller (not shown) that controls the operation to head toward the charging station S, and starts the power receiving control process of FIG. 4 to begin transmitting backup power transmission commands, etc. When the drive controller detects that the AGV 100 is approaching or has arrived at the charging station S, it stops the AGV 100 at a fixed position within the charging station S.

Therefore, when the received information is not a backup power transmission command, etc., it is, for example, when the AGV 100 is traveling away from the charging station S or is not stopped at the stop line within the charging station S, and information such as a backup power transmission command sent from the infrared units 57, 58 (hereinafter referred to as "infrared unit 57, etc.") of the power receiving device 15 does not reach the power transmitting device 12 and cannot be received by the infrared unit 27, etc. (the receiving buffer is empty). In other words, when the received information is not a backup power transmission command, etc., it is when the AGV 100 is not stopped at its regular position within the charging station S.

The communication between the infrared unit 27 of the power transmission device 12 and the infrared unit 57 of the power receiving device 15 is optical wireless communication using infrared rays, and the infrared rays (infrared light) transmitted (emitted) from the infrared unit 57 of the power receiving device 15 generally have a high degree of directionality due to the characteristics of an infrared emitting module that has a focusing part such as a lens. Therefore, when the infrared unit 27 of the power transmission device 12 receives a backup power transmission command, the AGV 100 is likely to be parked at its regular position in the charging station S.

In other words, the determination of whether infrared communication is possible between the power transmitting device 12 and the power receiving device 15 can also serve as a determination of the presence (stopped) of the AGV 100 at its fixed position in the charging station S. Therefore, if the determination process in step S105 determines that the information received in step S103 is a backup power transmission command and ID information (S105; Yes), it becomes possible to determine that the AGV 100 is stopped at its fixed position in the charging station S.

In this manner, in this embodiment, after the power is turned on, the power transmission device 12 of the charging station S continues to wait by repeatedly executing steps S103 and 105 until the backup power transmission command and ID information transmitted by the power receiving device 15 of the AGV 100 reach the power transmission device 12, that is, until the AGV 100 arrives at the charging station S. This state is shown diagrammatically in the sequence diagram in FIG. 5.

That is, as shown in FIG. 5, after powering on, the power transmission device 12 performs an initialization process (S101), and then continues to perform the first phase (S100) on the power transmission side, which includes a reception information acquisition process (S103) and a reception determination process (S105), until it is able to receive a backup power transmission command, etc. 81 transmitted from the power receiving device 15. As a result, when the AGV 100 stops at a fixed position in the charging station S, the power transmission device 12 can automatically transition to the process related to backup power transmission (S111 to S119) without any operation by an operator.

As mentioned above, the power receiving device 15 starts transmitting backup power transmission commands, etc. 81 before the AGV 100 carrying it arrives at the charging station S. Therefore, the dashed line with an arrow (symbol 81') in FIG. 5 represents a backup power transmission command, etc. that is sent from the power receiving device 15 but does not reach (cannot be received by) the power transmitting device 12 when the AGV 100 is away from the charging station S.

When it is determined in step S105 that the received information is a backup power transmission command or the like (S105; Yes), backup power transmission is started in the following step S111 (backup power transmission start process). Backup power transmission is performed by transmitting power from the power transmitting device 12 to the power receiving device 15 that is sufficiently smaller than the specified power during main power transmission (normal power transmission). In this embodiment, for example, pre-power equivalent to 1/10 (10%) of the specified power during main power transmission is transmitted (see FIG. 5). Note that in this embodiment, the specified power during main power transmission corresponds to the charging power of the battery 110. Also, the pre-power during backup power transmission may or may not contribute to charging the battery 110.

That is, the controller 26 performs switching control on the voltage converter 23 and the inverter 24 so that the power transmission coil 25 transmits a preset pre-power. Note that the pre-power is set within a range such that, even if the power transmission device 12 transmits power to the power receiving device 15 when the AGV 100 in the charging station S is parked slightly away from its fixed position in the charging station S (not parked at its fixed position), the power transmission unit 20 is unlikely to break down due to power reflection caused by impedance mismatch, etc., and electromagnetic waves generated by the power transmission are unlikely to have a physical adverse effect on workers working near or around the coil unit 31.

In the next step S113, a power transmission information acquisition process is performed. In this process, information obtained from the voltage sensors, current sensors, and temperature sensors provided in the voltage converter 23 and inverter 24 (information on the input voltage and current of the voltage converter 23, the output voltage and current of the inverter 24, and the internal temperatures of the voltage converter 23 and inverter 24) is acquired. This power transmission information is used in the next step S114 to determine whether an abnormality has occurred.

In step S114, a process is performed to determine whether or not an abnormality has occurred in the voltage converter 23 or the inverter 24 based on the power transmission information acquired in step S113. An abnormality may occur, for example, when the input voltage or current of the voltage converter 23 or the input/output voltage or current of the inverter 24 exceeds a predetermined maximum allowable value, or when the internal temperature of the voltage converter 23 or the inverter 24 exceeds a maximum allowable temperature.

When it is determined in step S114 that an abnormality has occurred in the voltage converter 23 or the inverter 24 (S114; Yes), the backup power transmission is terminated (S115), and information about the abnormality that has occurred (abnormality information) is output to a display panel or the like of an operation panel (not shown) on which the power transmission device 12 is provided (S131). In other words, the abnormality information is output to the outside of the power transmission device 12. Note that instead of (or in addition to) the abnormality information output process in step S131, the power transmission information acquisition process (corresponding to S113) and the abnormality occurrence determination process (corresponding to S114) are performed again, and if it is determined that the occurrence of the abnormality has been resolved, the process flow may be changed so that the process returns to the initial reception information acquisition process (S103) and is restarted from the beginning.

On the other hand, when it is determined in step S114 that no abnormality has occurred in the voltage converter 23 or the inverter 24 (S114; No), the process proceeds to the next step S116, where the received information acquisition process is performed. Due to the backup power transmission by the power transmission device 12, a pre-power that is sufficiently smaller than the specified power during main power transmission is transmitted to the power receiving device 15 via the power receiving coil 54. As a result, as described below, when the controller 56 of the power receiving device 15 detects that the pre-power has been normally received, the power receiving device 15 transmits a main power transmission command to the power transmission device 12, so in step S116, a process is performed to read out the main power transmission command that may have been received by the infrared unit 27 of the power transmission device 12 from the reception buffer.

In the next step S117, a process is performed to determine whether the infrared unit 27 or the like has received the actual power transmission command. If it is determined that the received information is not the actual power transmission command (S117; No), the process returns to step S113 again and the power transmission information acquisition process is performed. If it is determined in step S116 that the actual power transmission command cannot be read even after a predetermined time has elapsed (S117; Time's Up), there is a possibility that a problem has occurred with the AGV 100 or its power receiving device 15, so after completing backup power transmission (S119), the process returns to the initial received information acquisition process (S103) and starts the process over from the beginning.

On the other hand, if it is determined that the received information is a main power transmission command (S117; Yes), this means that the power receiving device 15 of the AGV 100 is normally receiving pre-power from the backup power transmission, and the backup power transmission is terminated in the following step S118.

Thus, in this embodiment, when the power transmission device 12 of the charging station S starts backup power transmission (S111), it continues to transmit preliminary power by repeatedly executing steps S113, S114, S116, and S117 until the main power transmission command transmitted by the power receiving device 15 of the AGV 100 reaches the power transmission device 12. That is, as shown in the sequence diagram of FIG. 5, after starting backup power transmission, the power transmission device 12 continues to transmit preliminary power by backup power transmission 91 by repeatedly performing the power transmission side second phase (S110) including the power transmission information acquisition process (S113), the abnormality determination process (S114), the reception information acquisition process (S116), and the reception determination process (S117) until the main power transmission command 83 transmitted from the power receiving device 15 can be received.

As a result, as described below, the power transmission device 12 continues transmitting pre-power and waits for main power transmission until the power receiving device 15 mounted on the AGV 100 is ready to receive power and can receive optimal power, so that main power transmission by the power transmission device 12 will not start before the power receiving device 15 is ready to receive power. Therefore, the power receiving device 15 is able to receive a specified amount of power from the main power transmission by the power transmission device 12 in an optimal state.

When the backup power transmission end process in step S118 is completed, a predetermined waiting time has elapsed, and then the main power transmission is started in the next step S121 (main power transmission start process). This predetermined waiting time is the interval time required when the power transmission unit 20 (voltage converter 23, inverter 24, etc.) switches the output from backup power transmission to main power transmission.

The power transmitted in this way (normal transmission) is the specified power that should be transmitted to the power receiving device 15, and is much larger than the pre-power of the backup power transmission. The specified power for this type of transmission is determined uniformly based on the specifications of the battery 110 and charging unit 53 equipped in the AGV 100, or is determined individually and specifically for each AGV 100 and power receiving device 15 in association with their respective IDs. The individual specified power is selected by the controller 26 based on the ID acquired in the reception information acquisition process (S103).

In the next step S123, a power transmission information acquisition process is performed. In this process, information obtained from the voltage sensors, current sensors, and temperature sensors provided in the voltage converter 23 and inverter 24 (information on the input voltage and current of the voltage converter 23, the output voltage and current of the inverter 24, and the internal temperatures of the voltage converter 23 and inverter 24) is acquired. This power transmission information is used in the next step S124 to determine whether an abnormality has occurred.

In step S124, a process is performed to determine whether or not an abnormality has occurred in the voltage converter 23 or the inverter 24 based on the power transmission information acquired in step S123. An abnormality may occur, for example, when the input voltage or current of the voltage converter 23 or the input/output voltage or current of the inverter 24 exceeds a predetermined maximum allowable value, or when the internal temperature of the voltage converter 23 or the inverter 24 exceeds a maximum allowable temperature.

When it is determined in step S124 that an abnormality has occurred in the voltage converter 23 or the inverter 24 (S124; Yes), the power transmission is terminated (S125), and information about the abnormality (abnormality information) is output to a display panel or the like (outside the power transmission device 12) of an operation panel (not shown) on which the power transmission device 12 is provided (S131). Note that, as described in the explanation of the abnormality occurrence determination process in step S114, instead of (or in addition to) the abnormality information output process in step S131, the power transmission information acquisition process (corresponding to S113) and the abnormality occurrence determination process (corresponding to S114) may be performed again, and the process flow may be changed so that if the abnormality is resolved, the process returns to the initial reception information acquisition process (S103).

In contrast, when it is determined in step S124 that no abnormality has occurred in the voltage converter 23 or the inverter 24 (S124; No), the process proceeds to the following step S126, where the received information acquisition process is performed. Since the power receiving device 15 of the AGV 100 receives power from this power transmission and charges the battery 110 using the charging unit 53, charging proceeds over time and eventually the charging of the battery 110 is completed.

As described below, when the controller 56 of the power receiving device 15 determines that the battery 110 is fully charged (charging completed) based on the state of the charging completion flag, the power receiving device 15 transmits a power transmission stop command to the power transmitting device 12, and when this is not the case (charging is not completed), the power receiving device 15 transmits the main power transmission command again to the power transmitting device 12. Therefore, in step S126, a process is performed to read out from the reception buffer the power transmission stop command and the main power transmission command that may have been received by the infrared unit 27 of the power transmitting device 12, etc.

In the next step S127, a process is performed to determine whether the infrared unit 27, etc. has received the main power transmission command. If it is determined that the received information is not the main power transmission command (S127; No), the process is performed in the next step S128 to determine whether the infrared unit 27, etc. has received a power transmission stop command. If it is determined in step S126 that the main power transmission command cannot be read even after the predetermined period Tw has elapsed (S127; Time's Up), there is a possibility that a problem has occurred in the AGV 100 or its power receiving device 15, so after completing the main power transmission (S129), the process returns to the initial received information acquisition process (S103) and starts over from the beginning. The predetermined period Tw is set to a time that is multiple times the time Tr required for the repeated processing in the second phase of the power receiving control processing described later.

On the other hand, if it is determined in step S127 that the received information is a power transmission command (S127; Yes) or if it is determined in step S128 that the received information is not a power transmission stop command (S128; No), the process returns to step S124 again to perform the abnormality occurrence determination process. If it is determined that the received information is a power transmission stop command (S128; Yes), charging of the battery 110 has been completed in the power receiving device 15 of the AGV 100, so the process ends the power transmission in the following step S129, and the process returns to the initial received information acquisition process (S103) to wait for another AGV 100 to arrive at the charging station S.

In this embodiment, when the power transmission device 12 of the charging station S starts the main power transmission (S121), it continues to transmit power by repeatedly executing steps S124, S126, S127, and S128 until the power transmission stop command transmitted by the power receiving device 15 of the AGV 100 reaches the power transmission device 12. That is, as shown in the sequence diagram of FIG. 5, after starting the main power transmission, the power transmission device 12 continues to receive the main power transmission command 85 repeatedly transmitted from the power receiving device 15 until it receives the power transmission stop command 87, by repeatedly performing the power transmission side third phase (S120) including the abnormality determination process (S124), the reception information acquisition process (S126), the main power transmission command reception determination process (S127), and the power transmission stop command reception determination process (S128), thereby continuing the main power transmission 93.

As a result, if the main power transmission command 85 cannot be received within the specified time period Tw (S127; Time's Up), the main power transmission end process (S129) is performed and the main power transmission is stopped. Therefore, for example, as shown in the sequence diagram shown in FIG. 6, if the AGV 100 moves from its fixed position in the charging station S and leaves the charging station S while the main power transmission 93 is being performed (while the battery 110 is being charged), the main power transmission is stopped and the specified power is no longer supplied to the AGV 100y. This makes it possible to prevent the occurrence of a situation in which the main power transmission is performed even when the AGV 100 is not present in the charging station S, resulting in a breakdown of the power transmission device 12.

If a power transmission stop button is provided on the operation panel (not shown) that houses the power transmission device 12, the algorithm of the power transmission control process described above may be configured so that the backup power transmission 91 or main power transmission 93 described above can be interrupted by operating the button. Also, if a communication stop button is provided on the operation panel, the algorithm of the power transmission control process described above may be configured so that communication with the power receiving device 15 can be cut off by operating the button.

Next, the power receiving control process executed by the controller 56 of the power receiving device 15 mounted on the AGV 100 will be described with reference mainly to Figures 4 to 6.

<Power Reception Control Processing>
When the power receiving device 15 is turned on, the controller 56 of the main unit 51 starts executing a battery monitoring program, and starts monitoring the terminal voltage (battery voltage) and terminal current (battery current) of the battery 110. If the controller 56 determines from this monitoring process that the battery 110 needs to be charged, it sends an instruction to the drive controller (not shown) that controls operation to move the AGV 100 toward the charging station S, and starts executing the power receiving control program. This starts the power receiving control process shown in FIG. 4.

In the power reception control process, a predetermined initialization process is first performed in step S201. In this process, for example, the work area and flags in the memory of the controller 56 are cleared, and control commands for initial setting are sent to the charging unit 53, the infrared unit 57, etc.

Then, in step S203, a process for transmitting a backup power transmission command, etc. is performed. As described above, the power receiving device 15 mounted on the AGV 100 starts transmitting a backup power transmission command, etc. 81' before the AGV 100 arrives at the charging station S. Therefore, in this power receiving control process, a process for transmitting a backup power transmission command, etc. 81' is performed almost immediately after the process starts. In other words, even if the AGV 100'' is traveling at a position away from the charging station S, the backup power transmission command, etc. 81' is transmitted (the power receiving device 15' represented by the dashed frame in Figure 5).

For example, the backup power transmission command and an ID capable of identifying the power receiving device 15 or the AGV 100 that is the sender are set in a transmission buffer, and a control command instructing transmission is output to the infrared unit 57, etc. The transmission buffer is secured in the memory of the infrared unit 57, etc., if the infrared unit 57, etc., has a memory, and is secured in the memory of the controller 56 if the infrared unit 57, etc. does not have such a memory.

In the next step S205, a receiving voltage information acquisition process is performed. In this process, voltage information received by the receiving coil 54 of the coil unit 61 is acquired. For example, in this embodiment, the charging unit 53 is provided with a voltage sensor (not shown) that detects the input voltage. Therefore, in this process, the voltage information detected by this voltage sensor is acquired as information on the receiving voltage of the receiving coil 54. If it is necessary to accurately obtain the receiving voltage of the receiving coil 54, it may be calculated based on the voltage information of this voltage sensor.

Then, the determination process in step S207 determines whether the receiving voltage obtained in step S205 is equal to or greater than a predetermined voltage value. This predetermined voltage value is the receiving voltage that the receiving coil 54 can receive when the AGV 100 is stopped at a fixed position in the charging station S in the case where the power transmission device 12 is transmitting pre-power by backup power transmission 91 in the second phase S110 of the power transmission side described above, and is set appropriately based on the results of experiments and computer simulations. Furthermore, the upper limit above the predetermined voltage value is within a predetermined tolerance range, and this tolerance range is also set appropriately based on the results of experiments and computer simulations.

In this step S207, it may be determined whether the voltage is at a predetermined value (predetermined value) rather than whether it is at or above a predetermined voltage value. It may also be determined whether the receiving current that the receiving coil 54 can receive is at or above a predetermined current value (predetermined value) or a predetermined current value (predetermined value), or whether the receiving power that can be received is at or above a predetermined power value (predetermined value) or a predetermined power value (predetermined value). The current value is obtained by a current sensor, and the power value is obtained by the controller 56 calculating the product of the voltage value and the current value.

If the power receiving voltage information acquired in step S205 is not equal to or greater than the predetermined voltage value, the predetermined current value, or the predetermined power value (hereinafter referred to as the "predetermined voltage value, etc.") (S207; No), the AGV 100' is unlikely to be parked at a fixed position in the charging station S, and may not have yet arrived at the charging station S. Therefore, in this case, the process returns to step S203, and a backup power transmission command, etc. 81' is transmitted by the backup power transmission command, etc. transmission process, and the power receiving voltage information acquisition process is performed again in step S205.

In contrast, if the power receiving voltage information acquired in step S205 is a predetermined voltage value or the like (S207; Yes), it is highly likely that pre-power is being received normally and the AGV 100 is parked at a fixed position within the charging station S. In other words, the power receiving device 15 is now ready to receive power, enabling optimal power reception. Therefore, in this case, the process proceeds to the next step S209, where the power transmission command transmission process is performed.

That is, since the AGV 100 is parked at a fixed position in the charging station S, for example, impedance mismatches are unlikely to occur, and there is a low possibility of problems occurring even if main power transmission is started. Therefore, in the main power transmission command transmission process in step S209, a main power transmission command 83 is transmitted to the power transmission device 12 as an instruction to switch from backup power transmission to main power transmission. For example, the main power transmission command is set in the transmission buffer, and a control command instructing transmission is output to the infrared unit 57, etc.

Note that if the acquired power receiving voltage information does not become equal to or greater than the predetermined voltage value (is less than the predetermined voltage value) even after steps S203 to S207 are repeated multiple times (e.g., 10 times) or for a predetermined period of time or more (e.g., 1 second or more), the power transmitting unit 20 or the power receiving unit 50 may be malfunctioning. Also, if the acquired power receiving voltage information is higher than the predetermined voltage value by exceeding the aforementioned allowable range, the power transmitting unit 20 may be malfunctioning. Therefore, in these cases, the power receiving control process may be terminated after the abnormality information output process (S235) described below is performed.

As described above, the drive controller (not shown) that controls the operation of the AGV 100 controls the steering and braking of the AGV 100 by image recognition of the guide lines G and stop lines displayed at fixed positions within the charging station S, but in addition to information obtained by such image recognition, control may be performed to correct the stopping position of the AGV 100 based on the power receiving voltage information obtained in step S205. In this case, a process of sequentially sending the power receiving voltage information obtained in step S205 to the drive controller is added to the power receiving control process.

As a result, for example, after performing braking control based on image recognition, the drive controller can perform driving control to move the AGV 100 forward or backward so that the predetermined voltage value, etc., due to power reception acquired in step S205 near the stopping position becomes a maximum value, thereby enabling the power receiving device 15 mounted on the AGV 100 to receive power from the power transmitting device 12 in an optimal positional relationship for contactless power supply.

In this embodiment, after starting the power receiving control process, the power receiving device 15 mounted on the AGV 100 performs the initialization process (S201) and then continues the power receiving side first phase (S200) including the backup power transmission command transmission process (S203), the power receiving voltage information acquisition process (S205) and the voltage value determination process (S207) until a predetermined voltage value is obtained as the voltage received by the power receiving coil 54.

As a result, the power receiving device 15 repeatedly transmits the backup power transmission command 81, 81' even before the AGV 100 arrives at the charging station S and stops at the fixed position, so when the power transmitting device 12 of the charging station S receives the backup power transmission command 81, there is a high probability that the AGV 100 is stopped at the fixed position in the charging station S. In other words, the power transmitting device 12's determination of whether or not infrared communication between the power transmitting device 12 and the power receiving device 15 is possible can also serve as a detection and determination of the stopping position (fixed position) in the charging station S. In addition, even without operation by an operator, the power receiving device 15 can notify the power transmitting device 12 that the AGV 100 on which it is mounted is present in the charging station S, and the power transmitting device 12 can confirm the presence of the AGV 100.

When the main power transmission command transmission process in step S209 is completed, the power transmission device 12 that received it ends the backup power transmission 91 as described above, and then starts main power transmission 93 after a predetermined waiting time has elapsed. Therefore, the controller 56 of the power receiving device 15 performs the battery charging start process in the next step S211 after a time equal to or longer than the predetermined waiting time has elapsed since the main power transmission command transmission process (S209) is completed. As a result, the controller 56 starts the battery charging process executed by another program, and controls the charging unit 53 so that charging appropriate for the current battery 110 can be performed.

In this battery charging process, the charging voltage and charging current are controlled using a charging method suitable for the type of battery cell of the battery 110. For example, if the battery cell is composed of a lithium ion secondary battery, charging is performed using a constant current, constant voltage (CC/CV (Constant Current, Constant Voltage) charging method, and if it is composed of a lead acid battery, charging is performed using a quasi-constant voltage charging method. Then, when the battery 110 is fully charged (charging completed), the battery charging process, for example, turns on a charging completion flag to notify this power receiving control process of the completion of charging and waits. By continuing charging without stopping it even during standby, charging current continues to flow to the battery 110 as the output destination of the specified power transmitted from the power transmitting device 12.

In the next step S213, the main power transmission command transmission process is performed. This process is the same as the main power transmission command transmission process in step S209 described above. For example, the main power transmission command is set in a transmission buffer, and a control command instructing transmission is output to the infrared unit 57 or the like. Note that the main power transmission command transmission process in step S209 is repeatedly executed until charging is completed, as described below. Therefore, as shown in FIG. 5, during the period during which the main power transmission 93 is being performed (while the battery 110 is being charged), the main power transmission command 85 is repeatedly transmitted from the power receiving device 15 to the power transmitting device 12 at a predetermined timing.

In the next step S214, a receiving voltage information acquisition process is performed. As in step S205 described above, voltage information detected by a voltage sensor that detects the input voltage of the charging unit 53 is acquired as voltage information received by the receiving coil 54 of the coil unit 61. In the next step S215, a battery information acquisition process is performed. In this process, information on the battery voltage, battery current, and cell temperature is acquired by the voltage sensor 113, battery current, and temperature sensors (not shown) provided in the battery 110.

The voltage information of the received voltage and the information of the battery 110 (voltage information, current information, temperature information) acquired by these are used in the abnormality determination process in the following step S217 to determine whether or not an abnormality has occurred in the receiving coil 54, the charging unit 53, or the battery 110.

When it is determined in step S217 that an abnormality has occurred in the power receiving coil 54, the charging unit 53, or the battery 110 (S217; Yes), the battery charging process is terminated (S231), a power transmission stop command is sent (S233), and information about the abnormality (abnormality information) is output to the operation panel or the like of the AGV 100 on which the power receiving device 15 is mounted (S235). In other words, the abnormality information is output to the outside of the power receiving device 15. Note that instead of (or in addition to) the abnormality information output process in step S235, the power receiving voltage information acquisition process (corresponding to S214), the battery information acquisition process (corresponding to S215), and the abnormality occurrence determination process (corresponding to S217) are performed again, and if it is determined that the abnormality has been eliminated, the flow of the process may be changed so that the charging completion determination process (S219) is returned to.

In contrast, if it is determined in step S217 that no abnormality has occurred in the battery 110 (S217; No), the charging completion determination process (S219) is performed in the following step S219. The determination process in step S219 is performed by referring to the charging completion flag described above. That is, when charging of the battery 110 is completed by the battery charging process, the charging completion flag is set to on as described above, and the determination process determines whether charging is complete based on the state of this flag.

If charging of the battery 110 is not complete (S219; No), the process returns to step S213 and performs the power transmission command transmission process again. If charging of the battery 110 is complete (S219; Yes), the process proceeds to the power transmission stop command transmission process in the next step S221. However, before the transition to step S221, the above-mentioned battery charging process is not stopped or ended, and control is performed so that a trickle charging circuit or float charging circuit (not shown) that flows a small charging current to the battery 110 and releases excess power to a discharge resistor or the like can be operated. This makes it possible to use the battery 110, etc. as an output destination (escape point) for the specified power transmitted from the power transmission device 12.

In this embodiment, after the power receiving device 15 mounted on the AGV 100 performs the battery charging start process (S211), it continues to perform the power receiving side second phase (S210) including the power transmission command transmission process (S213), the power receiving voltage information acquisition process (S214), the battery information acquisition process (S215), and the abnormality occurrence determination process (S217) until the charging of the battery 110 is completed. In other words, steps S213, S214, S215, S217, and S219 are repeatedly executed to repeatedly transmit the power transmission command at the predetermined timing Tm. The time (required time) Tr required for the repeated processing of steps S213, S214, S215, S217, and S219 corresponds to the interval of the predetermined timing Tm for repeatedly transmitting the power transmission command. This allows the power transmitting device 12 to be notified of the presence of the power receiving device 15 and the AGV 100 on which it is mounted, even during the power transmission period.

Therefore, for example, if the AGV 100 moves and leaves the charging station S during the main power transmission, the power transmission device 12 will not be able to receive the main power transmission command 85 within the specified period Tw, as described above. In such a case, as shown in FIG. 6, the power transmission device 12 can end the main power transmission 93 and stop supplying the specified power. In this case, the power receiving device 15 determines that an abnormality has occurred (S217; Yes) based on the information on the decrease in the power receiving voltage acquired in the power receiving voltage information acquisition process (S214) due to the sudden drop in the power receiving voltage of the power receiving coil 54. Therefore, the main power receiving control process ends via the battery charging end process (S231), the power transmission stop command transmission process (S233), and the abnormality information output process (S235).

When it is determined in step S219 that charging of the battery 110 is complete (S219; Yes), the specified power supplied by the power transmission device 12 through the main power transmission is no longer necessary. Therefore, since it is necessary to stop the main power transmission by the power transmission device 12, in the next step S221, a power transmission stop command 87 is sent to the power transmission device 12 as an instruction to stop the main power transmission. For example, the power transmission stop command is set in the transmission buffer, and a control command instructing transmission is output to the infrared unit 57, etc.

Then, in step S223, a process for acquiring received voltage information is performed. As in step S205 described above, the voltage information detected by the voltage sensor that detects the input voltage of the charging unit 53 is acquired as voltage information received by the receiving coil 54 of the coil unit 61. Then, in step S225, a determination is made based on the voltage information obtained in step S223 as to whether or not there is no receiving of power.

When the infrared unit 27 of the power transmitting device 12 receives the power transmission stop command 87 transmitted in step S221 and the power transmission is stopped (S128 shown in FIG. 3; Yes), the power receiving coil 54 of the power receiving device 15 will no longer receive power. Therefore, when it is determined that power is being received by the power receiving coil 54 (S225; No), steps S221, S223, and S225 are repeatedly executed until it is determined that no power is being received (S225; Yes).

If there is no power being received by the power receiving coil 54 (S225; Yes), even if the battery charging process is terminated, there is no surplus power (predetermined power) that can be input to the charging unit 53 if there is power being received by the power receiving coil 54. Therefore, since the charging unit 53 will not be damaged, the battery charging termination process is performed in step S227 and the battery charging process that has been on standby is terminated. This ends the series of power receiving control processes. After the AGV 100 has completed charging, it leaves the charging station S and travels along the guideline G toward the next destination (AGV 100x shown in FIG. 5).

In this embodiment, after charging of the battery 110 is completed (S219; Yes), the power receiving device 15 mounted on the AGV 100 continues to perform the power receiving side third phase (S220), which includes the power transmission stop command transmission process (S221), the power receiving voltage information acquisition process (S223), and the power receiving determination process (S225), until the power receiving coil 54 of the coil unit 61 is no longer receiving power, and after confirming that the power receiving coil 54 is no longer receiving power (S225; Yes), it ends the battery charging process (S227).

As a result, while power is being received by the receiving coil 54, the charging current is controlled to continue to flow to the battery 110 without stopping or terminating the battery charging process. By using the battery 110 or a discharge resistor, etc. as an output destination (escape route) for the specified power transmitted from the power transmission device 12, it is possible to reduce damage to the charging unit 53 and the power transmission device 12 compared to a case where there is no escape route for such received specified power (surplus power).

If a charging stop button is provided on the operation panel of the AGV 100 on which the power receiving device 15 is mounted, the algorithm of the power receiving control process described above may be configured so that the power receiving control process can be forcibly terminated by operating the button via the battery charging termination process (S231), the power transmission stop command transmission process (S233), and the abnormality information output process (S235).

As described above, in the charging system 10 of this embodiment, the infrared unit 57 of the power receiving device 15 mounted on the AGV 100 transmits information to the infrared unit 27 of the power transmitting device 12, etc., by infrared communication, which has sharper directionality than radio waves due to the characteristics of an infrared emitting module that generally has a light collecting part such as a lens, although this depends on the type of radio wave transmission antenna. Since the infrared unit 57 of the power receiving device 15 repeatedly transmits backup power transmission commands, etc. (ID and backup power transmission command) 81, 81' before the AGV 100 stops at the charging station S, when the infrared unit 27 of the power transmitting device 12 receives the backup power transmission command, etc. 81, it is highly likely that the AGV 100 is stopped at the charging station S. Therefore, in such a case, in the power transmitting device 12, the power transmitting unit 20 starts backup power transmission 91, in which a pre-power sufficiently smaller than the predetermined power at the time of main power transmission 93 is supplied.

As a result, when the AGV 100 stops at a fixed position in the charging station S, the power transmission device 12 automatically starts backup power transmission 91 prior to main power transmission 93. Therefore, even if the power transmission device 12 performs backup power transmission 91 to the power receiving device 15 when the AGV 100 is stopped slightly away from its fixed position in the charging station S, the power transmission unit 20 is unlikely to break down due to power reflection caused by impedance mismatch, etc., and electromagnetic waves generated by the backup power transmission 91 are unlikely to have a physical adverse effect on workers working near or around the coil unit 31. Therefore, a predetermined amount of power can be safely and automatically supplied to the AGV 100.

In addition, in the charging system 10 of this embodiment, the controller 56 of the power receiving device 15 controls the infrared unit 57, etc. to transmit a main power transmission command 83 requesting the transmission of a predetermined power via the infrared unit 57, etc. when the pre-power received by the backup power transmission 91 is a predetermined voltage value, etc. Furthermore, the controller 26 of the power transmitting device 12 controls the power transmitting unit 20 to start the main power transmission 93 when the infrared unit 27, etc. receives the main power transmission command 83. If the received power is lower than the predetermined voltage value, etc., for example, the AGV 100 may be parked slightly off-center from its fixed position in the charging station S, or the power transmitting unit 20 or the power receiving unit 50 may be malfunctioning. If the received power is higher than the predetermined voltage value, etc. beyond the allowable range, for example, the power transmitting unit 20 may be malfunctioning.

As a result, when the power received by the backup power transmission 91 is not at a predetermined voltage value, etc., the main power transmission command 83 is not sent, making it possible to avoid starting the main power transmission 93 when the AGV 100 is parked away from its designated position in the charging station S or when there is a possibility that the power transmission unit 20 or the power receiving unit 50 is malfunctioning. Therefore, the specified power from the main power transmission 93 is supplied to the AGV 100 only when the AGV 100 is properly parked at its designated position in the charging station S or when both the power transmission unit 20 and the power receiving unit 50 are normal, further improving safety.

Furthermore, in the charging system 10 of this embodiment, the controller 56 of the power receiving device 15 controls the infrared unit 57, etc. to repeatedly transmit the main power transmission command 85 via the infrared unit 57, etc. at a predetermined timing Tm during the period in which the power receiving unit 50 is receiving a predetermined power. Furthermore, the controller 26 of the power transmitting device 12 controls the power transmitting unit 20 to stop the main power transmission 93 if the infrared unit 27, etc. does not receive the main power transmission command 85 within a predetermined period Tw that includes multiple predetermined timings Tm.

As a result, even if the infrared unit 57 of the power receiving device 15 etc. repeatedly transmits the main power transmission command 85 at the specified timing Tm, if, for example, the AGV 100 moves and leaves its fixed position in the charging station S while receiving the specified power, or if the power receiving section 50 of the power receiving device 15 breaks down, the infrared unit 27 of the power transmitting device 12 etc. will not be able to receive the main power transmission command 85 within the specified period Tw, and the power transmitting device 12 will be able to automatically stop the main power transmission 93. Therefore, the specified power from the main power transmission 93 continues to be supplied to the AGV 100 only when the AGV 100 is properly parked in its fixed position in the charging station S or the power receiving device 15 is normal, further improving safety.

In the charging system 10 of this embodiment, the power transmitting device 12 uses an infrared unit 28 capable of transmitting and receiving, which has a transmitting function in addition to a receiving function, instead of the infrared unit 27 dedicated to receiving. Also, in the power receiving device 15, an infrared unit 58 capable of transmitting and receiving, which has a transmitting function in addition to a receiving function, instead of the infrared unit 57 dedicated to transmitting, is used. Therefore, the controller 26 of the power transmitting device 12 and the controller 56 of the power receiving device 15 can perform infrared wireless communication (optical wireless communication) in both directions. For example, the controller 26 of the power transmitting device 12 transmits the ID and information related to the ID received by the infrared unit 28 functioning as a receiver to the infrared unit 58 of the power receiving device 15 via the infrared unit 28 functioning as a transmitter, and the information is transmitted to the controller 56.

This allows the power transmitting device 12 to inform the power receiving device 15 of the ID it has received and, as information related to that ID, information that the power receiving device 15 having that ID has been recognized, registered, or authenticated and is now in a state where they can communicate with each other (pairing has been established). In addition, the power receiving device 15 can confirm that the power transmitting device 12 has received the ID it has sent and recognized, registered, or authenticated the power receiving device 15, and that as a result they have become in a state where they can communicate with each other (pairing has been established).

In the charging system 10 of the embodiment described above, the power transmitting device 12 is configured to include an infrared unit 27 capable of receiving information via optical wireless communication and an infrared unit 28 capable of transmitting and receiving information, and the power receiving device 15 is configured to include an infrared unit 57 capable of transmitting information via optical wireless communication and an infrared unit 58 capable of transmitting and receiving information. However, in another embodiment of the present invention, for example, as shown in Figures 7(A) and 7(B), the power transmitting device 12 and the power receiving device 15 may be configured to include wireless units 29, 59 capable of wireless communication with each other at short distances.

That is, as shown in FIG. 7(A), the power transmitting device 12 includes, in addition to the infrared unit 27, etc., a wireless unit 29 capable of short-range wireless data communication as a wireless unit connected to the controller 26. Also, as shown in FIG. 7(B), the power receiving device 15 includes, in addition to the infrared unit 57, etc., a wireless unit 59 capable of short-range wireless data communication as a wireless unit connected to the controller 56. These wireless units 29, 59 are compliant with wireless standards such as Bluetooth (registered trademark) and ZigBee (registered trademark).

Therefore, the controller 26 of the power transmitting device 12 transmits the ID of the power receiving device 15 received by the infrared units 27, 28 and pairing establishment information indicating that the power receiving device 15 having the ID has been recognized, registered or authenticated and is now in a state where mutual communication is possible, via the wireless unit 29 of the power transmitting device 12 to the wireless unit 59 of the power receiving device 15, and conveys this to the controller 56. Wireless communication by the wireless units 29, 59 uses radio waves as an information transmission medium, and although it depends on the type of transmitting antenna, radio waves are generally less directional and more likely to reach a wide range than optical wireless communication using infrared rays (infrared light) of the infrared units 27, 28, 57, 58 that have a focusing part such as a lens as a medium.

As a result, even in an environment where infrared wireless communication using infrared units 27, 28, 57, and 58 is difficult to transmit to infrared units 57 and 58 of power receiving device 15, by using radio waves as an information transmission medium, power receiving device 15 can reliably inform power receiving device 15 that the power transmitting device 12 has received the ID it transmitted and recognized the power receiving device 15, and that the power receiving device 15 has been recognized, registered, or authenticated and is now in a state where it can communicate with the power receiving device 15.

Wireless data communication is typically capable of transmitting and receiving larger volumes of data than optical wireless data communication such as infrared data communication. Therefore, various information related to the received pre-power and specified power, as well as other information, can be transmitted from the wireless unit 59 of the power receiving device 15 to the wireless unit 29 of the power transmitting device 12 and transmitted to its controller 26. Various information related to the backup power transmission 91 and main power transmission 93, as well as other information, can also be transmitted from the wireless unit 29 of the power transmitting device 12 to the wireless unit 59 of the power receiving device 15 and transmitted to its controller 56.

In the above embodiment, the main unit 21 and the coil unit 31 of the power transmission device 12 are configured to be separate from each other, but the main unit 21 and the coil unit 31 may be configured to be housed in the same housing. Also, the main unit 51 and the coil unit 61 of the power reception device 15 are configured to be separate from each other, but the main unit 51 and the coil unit 61 may be configured to be housed in the same housing.

In the above embodiment, the coil unit 31 of the power transmission device 12 is configured to be embedded in the floor F of the charging station S, but as long as the coil unit 31 is located in a position that does not interfere with the travel of the AGV 100, it may be mounted on a pillar or side wall beside the travel route so that it faces the side of the AGV 100 from the side of the travel route in the charging station S. In this case, the coil unit 61 of the power receiving device 15 mounted on the AGV 100 must be able to face the coil unit 31 beside the travel route, so that the coil unit 61 is mounted on a side panel or side member of the AGV 100.

Furthermore, in the above embodiment , the contactless power supply system of the present invention has been described as being applied to the charging system 10 of an AVG, but the application of the present invention is not limited to this, and the present invention can also be applied to, for example, a charging system for a self-propelled or walking robot, etc., as long as the system is capable of supplying power contactlessly and includes a power transmitting side device and a power receiving side device capable of communicating information at least from the power receiving side to the power transmitting side by optical wireless communication using an infrared communication unit, etc. In this case as well, the same technical actions and effects as those described above can be obtained.

Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications or changes to the above specific examples. Furthermore, the technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings achieves multiple objectives simultaneously, and achieving one of these objectives is itself technically useful. Note that the descriptions in parentheses in the [Explanation of symbols] column may clearly indicate the correspondence between the terms used in each of the above-mentioned embodiments and the terms described in the claims.

10...Charging system (non-contact power supply system)
REFERENCE SIGNS LIST 12 power transmitting device 15 power receiving device 18 AC power source 20 power transmitting section 25 power transmitting coil 26 controller (power transmitting side control section)
27...Infrared unit (receiver)
28...Infrared unit (transmitter, transmitter/receiver)
29, 59...Wireless unit (wireless section)
31, 61: Coil unit 50: Power receiving section 54: Power receiving coil 56: Controller (power receiving side control section)
57...Infrared unit (transmitter)
58...Infrared unit (receiver, transmitter/receiver)
81, 81': Reserve power transmission command, etc. (power transmission request information)
83, 85...Main power transmission command (normal power transmission request information)
87: Power transmission stop command 91: Backup power transmission 93: Main power transmission (normal power transmission)
100...AGV (mobile vehicle)
110: Battery 113: Voltage sensor 115: Current sensor F: Floor G: Guide line S: Charging station ( stop range )
Tr: Required time Tm: Predetermined timing Tw: Predetermined period

Claims (5)

a power receiving device that is provided in a moving body that stops within a stopping range for charging and that receives a supply of power in a wireless manner ;
a power transmitting device that is provided in the stopping range of the moving body and transmits power to the power receiving device,
The power receiving device includes a power receiving unit capable of receiving transmitted power in a wireless manner, a transmission unit capable of transmitting information by optical wireless communication, and a power receiving side control unit capable of controlling the power receiving unit and the transmission unit,
the power transmitting device includes a power transmitting unit capable of contactlessly transmitting the power to the power receiving unit, a receiving unit capable of receiving the information from the transmitting unit via the optical wireless communication, and a power transmitting side control unit capable of controlling the power transmitting unit and the receiving unit;
the power receiving side control unit controls the transmission unit to repeatedly transmit identification information capable of identifying the power receiving device or the moving body and power transmission request information requesting the transmission of power sufficiently smaller than a predetermined power of normal power transmission, from before the moving body stops in the stop range ;
The wireless power supply system is characterized in that, when the receiving unit receives the identification information and the power transmission request information, the power transmitting side control unit controls the power transmitting unit to start backup power transmission, which transmits power sufficiently smaller than the specified power , before performing normal power transmission based on normal power transmission request information requesting the transmission of the specified power. the power receiving-side control unit controls the transmission unit to transmit the normal power transmission request information via the transmission unit when the power received by the backup power transmission is a predetermined value;
The contactless power supply system according to claim 1 , wherein the power transmitting side control unit controls the power transmitting unit to start the normal power transmission when the receiving unit receives the normal power transmission request information. the power receiving side control unit controls the transmission unit to repeatedly transmit the normal power transmission request information at a predetermined timing via the transmission unit during a period in which the power receiving unit receives the predetermined power;
The wireless power supply system according to claim 1 or 2, characterized in that the power transmitting side control unit controls the power transmitting unit to stop the normal power transmission if the receiving unit does not receive the normal power transmission request information within a specified period that includes multiple specified timings. the power receiving device includes a receiving unit capable of receiving information via optical wireless communication in addition to the transmitting unit,
the power transmitting device includes a transmitting unit capable of transmitting information by optical wireless communication in addition to the receiving unit,
The contactless power supply system according to any one of claims 1 to 3, characterized in that the power transmitting side control unit transmits the identification information or information related to the identification information received by the receiving unit of the power transmitting device to the receiving unit of the power receiving device via the transmitting unit on the power transmitting device side, and conveys it to the power receiving side control unit. the power receiving device and the power transmitting device each include a wireless unit capable of wirelessly communicating with each other at a short distance;
The contactless power supply system according to any one of claims 1 to 4, characterized in that the power transmitting side control unit transmits the identification information or information related to the identification information received by the receiving unit of the power transmitting device to the wireless unit of the power receiving device via the wireless unit of the power transmitting device, and conveys it to the power receiving side control unit.

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