WIRELESS POWER FEEDING SYSTEM HAVING TUNING ADJUSTMENT CIRCUIT

摘要

[Problem] To perform wireless power feeding using an existing electronic device. [Solution] In the present invention, a power feeder has a power feeding coil. A power receiver has a power receiving coil, a power receiving circuit unit, and a load. Electromagnetic induction using a resonance phenomenon causes the power feeder to supply an electric energy to the power receiver. A switching circuit enables the power feeding coil to periodically repeat turning on (driving state) and turning off (resonant state) of power supply. A resonant frequency of the power receiver is substantially a period combining a time of the driving state and a time of the resonant state. A resonant frequency of the power feeder is substantially a period of the time of the resonant state, and a tuning adjusting circuit performs adjustment of a resonant capacitor and a coil. A driving pulse is turned on at a timing when a resonant coil voltage becomes a vicinity of a zero value, and the resonant coil voltage is kept to be the vicinity of the zero value during when the driving pulse is turned on. While the driving pulse is turned on, a driving current the upper limit of which is a resonant coil current flows.