Wireless power transmission device

A wireless power transmission device, comprising:

• a power transmission device;
• and
• a power reception device, to which power is transmitted from the power transmission device, wherein
• the power reception device includes
• a power reception coil which receives the power,
• a first resonance circuit connected to the power reception coil,
• a load circuit to which a first signal having a first power value is supplied from the first resonance circuit,
• a first power measuring unit which measures the first power value, and
• a transmitter which transmits the first power value to the power transmission device, and
• the power transmission device includes
• a power source which generates a second signal having a second power value,
• a second resonance circuit including a plurality of inductors and capacitors to which the second signal is input,
• a power transmission coil connected to the second resonance circuit, which transmits the power,
• a second power measuring unit which measures the second power value,
• a receiver which receives the first power value from the first transceiver, and
• a first control circuit which calculates power transmission efficiency using the first power value and the second power value and adjusts a frequency of the second signal output from the power source based on the power transmission efficiency.

A power transmission device, which transmits power to a power reception device, comprising:

• a power source which generates a first signal having a first power value;
• a first resonance circuit including a plurality of inductors and capacitors to which the first signal is input;
• a power transmission coil connected to the first resonance circuit which transmits the power;
• a power measuring unit which measures the first power value;
• a receiver which receives a second power value of a second signal supplied from a second resonance circuit connected to a power reception coil to a load circuit in the power reception device transmitted from the power reception device;
• and
• a control circuit which calculates power transmission efficiency using the first power value and the second power value and adjusts at least one of inductance values of the inductors and/or at least one of capacitance values of the capacitors based on the power transmission efficiency.

A power reception device, to which power is transmitted from a power transmission device, comprising:

• a power reception coil which receives the power;
• a resonance circuit including a plurality of inductors and capacitors and connected to the power reception coil;
• a load circuit to which a first signal having a first power value is supplied from the resonance circuit;
• a power measuring unit which measures the first power value;
• a transceiver which transmits the first power value to the power transmission device and receives power transmission efficiency calculated based on a second power value of a second signal generated by a power source for transmitting the power in the power transmission device and the first power value from the power transmission device;
• and
• a control circuit which adjusts at least one of inductance values of the inductors and/or at least one of capacitance values of the capacitors included in the resonance circuit based on the power transmission efficiency.