FIELD: electrical engineering.
SUBSTANCE: to be used in electrical engineering. Wireless power feeding system includes power transmission device (10c) having power transmission coil (14), and power receiving device (40) with power receiving coil (41). Power receiving device (40) includes first efficiency calculation unit (55) configured to calculate the first efficiency based on the value of the transmission power and electric power control command, supplied to storage battery (44). Power transmission device (10c) includes second efficiency calculation unit (31) configured to calculate a second efficiency based on the phase difference between the voltage and current supplied to power transmission coil (14). Power transmission device (10c) further includes control value calculation unit (29) configured to control the electric power supplied to power transmission coil (14), according to the value of the transmission power control command, and adjust the electric power supplied to power transmission coil (14) when the first efficiency drops to a predetermined first threshold efficiency or less, or when the second efficiency drops to a predetermined second threshold efficiency or less.
EFFECT: technical result is the possibility of adjusting the power transmission when the power transmission coils and power receiving coils are displaced relative to each other.
1 cl, 17 dwg
