Noncontact electric power feeding apparatus, noncontact electric power receiving apparatus, noncontact electric power feeding method, noncontact electric power receiving method, and noncontact electric power feeding system

A noncontact electric power receiving apparatus, comprising:

• a resonance element to receive an alternating current (A/C) electric power without contact with an electric power feeding source and in accordance with a resonance of a resonance element of the electric power feeding source;
• a rectifying circuit to create a direct current (D/C) electric power from the A/C electric power received through said resonance element and to output the D/C electric power;
• and
• an automatic impedance adjusting circuit provided between said resonance element and said rectifying circuit to variably control an impedance in accordance with a magnitude of a coupling coefficient between said noncontact electric power receiving apparatus and said electric power feeding source of the A/C electric power, the automatic impedance adjusting circuit including a three-port directional coupler coupled between the resonance element and the rectifying circuit to measure a magnitude of a reflected electric power, the coupling coefficient being determined by the automatic impedance adjusting circuit in accordance with the magnitude of a reflected electric power.

A noncontact electric power feeding method, comprising:

• measuring a magnitude of a reflected power using a three-port directional coupling coupled between an alternating current (A/C) power source that generates A/C power and an electric power feeding destination of the A/C electric power;
• determining a coupling coefficient based on the magnitude of the reflected power;
• and
• variably controlling an impedance in accordance with the coupling coefficient determined from the magnitude of the reflected power, the coupling coefficient being representative of a coupling between said A/C power source and a resonance element that supplies the A/C electric power from said A/C power source to another electronic apparatus without contacting the other electronic apparatus.

A noncontact electric power receiving method, comprising:

• measuring a magnitude of a reflected power using a three-port directional coupling coupled between a resonance element of an electric power feeding source of an alternating current (A/C) electric power and a rectifying circuit that creates a direct current (D/C) electric power from the A/C electric power received through said resonance element to output the D/C electric power;
• determining a coupling coefficient based on the magnitude of the reflected power;
• and
• variably controlling an impedance in accordance with a magnitude of the coupling coefficient determined from the magnitude of the reflected power, the coupling coefficient being representative of a coupling between the electric power feeding source and the electric power feeding destination that receives the A/C electric power without contact.

A noncontact electric power feeding system, comprising:

• a noncontact electric power feeding apparatus including:
• a resonance element to supply an (A/C) alternating current electric power without contact and in accordance with a resonance,
• an A/C power source configured to generate the A/C electric power to be supplied to said resonance element, and
• an automatic impedance adjusting circuit provided between said A/C power source and said resonance element to variably control an impedance in accordance with a coupling coefficient between said noncontact electric power feeding apparatus and an electric power feeding destination of the A/C electric power, the automatic impedance adjusting circuit including a three-port directional coupler coupled between the resonance element and the A/C power source to measure a magnitude of a reflected electric power, the coupling coefficient being determined by the automatic impedance adjusting circuit in accordance with the magnitude of a reflected electric power;
• and
• a noncontact electric power receiving apparatus including:
• a resonance element to receive the A/C electric power without contact and in accordance with a resonance from said resonance element of said noncontact element power feeding apparatus,
• a rectifying circuit to create a direct current (D/C) electric power from the A/C electric power received through said resonance element and to output the D/C electric power, and
• an automatic impedance adjusting circuit provided between said resonance element and said rectifying circuit to variably control an impedance in accordance with a magnitude of a coupling coefficient between said noncontact electric power receiving apparatus and said electric power feeding source of the A/C electric power, the automatic impedance adjusting circuit including a three-port directional coupler coupled between the resonance element and the rectifying circuit to measure a magnitude of a reflected electric power, the coupling coefficient being determined by the automatic impedance adjusting circuit in accordance with the magnitude of a reflected electric power.