Power feeding system, power feeding device, and power feeding method

A power feeding device configured to supply electric power to a power receiving device through electromagnetic induction,

• the power receiving device comprising:
• a resonant circuit having:
• a receiving coil configured to receive the electric power from a feeding coil;
• a resonant capacitor configured to resonate with the receiving coil;
• and
• a first switching element configured to perform switching between a resonant state and a non-resonant state by changing an electrical connection state of the resonant capacitor;
• and
• a resonance control unit configured to control the first switching element based on received power by the receiving coil from the feeding coil, and power consumption of a load to which the received power is supplied,
• the power feeding device comprising:
• a second switching element connected in series to the feeding coil;
• a drive signal generation unit configured to generate a drive signal for driving the feeding coil by switching the second switching element between a conductive state and a non-conductive state;
• a variation detection unit configured to detect the change in electrical connection state of the resonant capacitor as a periodic waveform variation in an excited voltage excited in the feeding coil;
• a variable power supply configured to vary a voltage value of a drive voltage supplied to the feeding coil;
• and
• a power feeding control unit configured to control the voltage value of the drive voltage supplied to the feeding coil based on a period of the resonant state and a period of the non-resonant state that are estimated from the periodic waveform variation detected by the variation detection unit.

A power feeding device configured to supply electric power, through electromagnetic induction, to a power receiving device having a receiving coil, a resonant capacitor configured to resonate with the receiving coil, and a first switching element configured to perform switching between a resonant state and a non-resonant state of the resonant capacitor,

• the power feeding device comprising:
• a feeding coil;
• a second switching element connected in series to the feeding coil;
• a drive signal generation unit configured to generate a drive signal for driving the feeding coil by switching the second switching element between a conductive state and a non-conductive state;
• a variation detection unit configured to detect a change in electrical connection state of the resonant capacitor as a periodic waveform variation in an excited voltage excited in the feeding coil;
• a variable power supply configured to vary a voltage value of a drive voltage supplied to the feeding coil;
• and
• a power feeding control unit configured to control the voltage value of the drive voltage supplied to the feeding coil based on a period of the resonant state and a period of the non-resonant state that are estimated from the periodic waveform variation detected by the variation detection unit.

A power feeding method for a power feeding system configured to supply electric power from a power feeding device to a power receiving device through electromagnetic induction,

• the power receiving device comprising a resonant circuit having a receiving coil configured to receive electric power, a resonant capacitor configured to resonate with the receiving coil, and a first switching element configured to perform switching between a resonant state and a non-resonant state by changing an electrical connection state of the resonant capacitor,
• the power feeding device comprising a feeding coil, a second switching element connected in series to the feeding coil, and a variable power supply coupled to the feeding coil and configured to supply a drive voltage having a variable voltage value to the feeding coil,
• the power feeding method comprising:
• generating a drive signal by the power feeding device for driving the feeding coil by switching the second switching element between a conductive state and a non-conductive state;
• controlling the first switching element by the power receiving device based on received power by the receiving coil from the feeding coil, and power consumption of a load to which the received power is supplied;
• detecting the change in electrical connection state of the resonant capacitor by the power feeding device as a periodic waveform variation in an excited voltage excited in the feeding coil;
• and
• controlling the variable voltage value of the drive voltage supplied to the feeding coil by the variable power supply based on a period of the resonant state and a period of the non-resonant state estimated from the periodic waveform variation.