Power transmitting device, electronic equipment and wireless power transmission system

An electronic device configured to receive electric power from a power transmission device, the power transmission device including a primary power transmission coil and a power transmission circuit supplying electric power to the primary power transmission coil, the electronic device comprising:

• a secondary power reception coil;
• and
• a power reception circuit that receives electric power transmitted from the primary power transmission coil via the secondary power reception coil,
• wherein a second impedance which corresponds to an output impedance of a transmission circuit, including the primary power transmission coil and the secondary power reception coil coupled to the primary power transmission coil, and to an impedance of the power reception circuit, is matched with a first impedance which corresponds to an input impedance of the transmission circuit and to an impedance of the transmission circuit seen by the power transmission circuit, by using a coupling coefficient between the primary power transmission coil and the secondary power reception coil,
• wherein, when the power transmission circuit supplies AC electric power at angular frequency ω to the primary power transmission coil,
• ωL1=Z1/K
• ωL2=Z2/K,
• where L1 is a first inductance of the primary power transmission coil, L2 is a second inductance of the secondary power reception coil, Z1 is the first impedance, Z2 is the second impedance, and K is the coupling coefficient.

A wireless power transmission system, comprising:

• a transmission circuit including a primary power transmission coil and a secondary power reception coil coupled to the primary power transmission coil;
• a power transmission circuit that transmits power via the primary power transmission coil;
• and
• a power reception circuit that receives power transmitted from the primary power transmission coil via the secondary power reception coil,
• wherein a first impedance which corresponds to an input impedance of the transmission circuit and to an impedance of the power transmission circuit seen by the power transmission circuit, is matched with a second impedance which corresponds to an output impedance of the transmission circuit and to an impedance of the power reception circuit, by using a coupling coefficient between the primary power transmission coil and the secondary power reception coil,
• wherein, when the power transmission circuit supplies AC electric power at angular frequency ω to the primary power transmission coil,
• ωL1=Z1/K
• ωL2=Z2/K,
• where L1 is a first inductance of the primary power transmission coil, L2 is a second inductance of the secondary power reception coil, Z1 is the first impedance, Z2 is the second impedance, and K is the coupling coefficient.