Wireless power transfer system that performs power transfer from determined power transmission device to power receiving device, power transmission device, power receiving device, and control method of wireless power transfer system

A control method of a wireless power transfer system that includes a power receiving device and a plurality of power transmission devices performing power transfer to the power receiving device, the system being communicably connected to a position information providing device that acquires a current position of the power receiving device, the method comprising:

• the power receiving device
• transmitting request-power to the power transmission device, the request-power being power the power receiving device requests to be supplied with,
• the power transmission device
• when receiving the request-power from the power receiving device, generating determination reference information based on the received request-power, the determination reference information being information to be used as a determination reference when the power receiving device selects the power transmission device, and
• transmitting the generated determination reference information to the power receiving device,
• the power receiving device
• receiving the determination reference information,
• selecting, based on the determination reference information, the power transmission device from which the power receiving device is to receive power supply, and
• transmitting a power transmission start request to the selected power transmission device, and
• the power transmission device
• starting power transfer to the power receiving device when receiving the power transmission start request,
• acquiring a current position of the power receiving device from the position information providing device,
• obtaining a distance from the power transmission device to the power receiving device based on the acquired current position,
• obtaining transmission efficiency in transferring power to the power receiving device, the transmission efficiency corresponding to the obtained distance,
• generating the determination reference information based on the received request-power and the obtained transmission efficiency, and
• transmitting the generated determination reference information to the power receiving device, and
• the position information providing device
• including a plurality of antennas arranged adjacent to one another, the plurality of antennas receiving a positioning signal that is a wireless signal to be transmitted from the power receiving device,
• obtaining a direction α where the power receiving device exists as seen from the position information providing device, based on a phase difference of the received positioning signals, and
• obtaining a current position of the power receiving device based on the obtained direction.