Wireless power transmission apparatus and wireless power transmission method

1. A wireless power transmission apparatus comprising:

a source resonator to transmit resonance power to a target resonator;

a coupling unit to couple a reflected signal with respect to the transmitted resonance power;

a resonance point detecting unit to scan a frequency band of the reflected signal, verify an amplitude of the reflected signal corresponding to the frequency band, and determine a coupling frequency based on the amplitude, wherein the source resonator and the target resonator are coupled at the coupling frequency;

a control unit configured to calculate a frequency deviation between a resonance frequency of the source resonator and the coupling frequency, and calculate an impedance deviation corresponding to the frequency deviation; and

an impedance control unit to adjust the impedance of the source resonator based on the impedance deviation,

wherein the impedance of the source resonator is adjusted by changing a distance between a conducting portion of the source resonator and a conductor of a matcher being electrically connected with the source resonator.

2. The apparatus of claim 1 , wherein the resonance point detecting unit comprises:

a level adjusting unit to adjust a signal level of the reflected signal;

a power level detecting unit to detect a power level of the adjusted reflected signal; and

a frequency scanning unit to perform frequency scanning with respect to the detected power level.

3. The apparatus of claim 2 , wherein the resonance point detecting unit further comprises:

a frequency synthesizer to output a frequency signal indicating a shifted level of a frequency of an alternating current (AC) signal that shifted due to an effect of the reflected signal, wherein the AC signal is converted by an AC converter.

4. The apparatus of claim 1 , wherein the impedance control unit sets an impedance set value for a maximal power transmission to be 33 ohms to 55 ohms.

5. The apparatus of claim 1 , wherein the impedance control unit adjusts the impedance of the source resonator to achieve a wireless power transmission efficiency that is above a threshold value.

6. A wireless power transmission method comprising:

performing frequency scanning with respect to a reflected signal of a transmitted resonance power;

determining a coupling frequency based on an amplitude of the reflected signal, wherein a source resonator and a target resonator are coupled at the coupling frequency;

calculating a frequency deviation between a resonance frequency and the coupling frequency;

calculating an impedance deviation corresponding to the frequency deviation; and

adjusting the impedance of the source resonator based on the impedance deviation,

wherein the impedance of the source resonator is adjusted by changing a distance between a conducting portion of the source resonator and a conductor of a matcher being electrically connected with the source resonator.

7. The method of claim 6 , wherein the detecting comprises:

adjusting a signal level of the reflected signal;

converting the adjusted reflected signal level into a direct current (DC) signal; and

performing frequency scanning with respect to the reflected signal having the adjusted signal level.

8. The method of claim 6 , wherein the detecting comprises:

synthesizing a frequency of an alternating current (AC) signal converted by an AC converter and a frequency of the reflected signal to output a frequency signal indicating a shifted level of the frequency of the AC signal that shifted due to an effect of the reflected signal; and

converting the frequency signal into a DC signal.

9. The method of claim 6 , wherein the adjusting comprises:

adjusting the impedance of the source resonator to be 33 ohms to 55 ohms based on the impedance deviation.

10. The method of claim 6 , wherein the impedance is adjusted to achieve a wireless power transmission efficiency that is above a threshold value.

11. A wireless power receiving device comprising:

a target resonator configured to receive power wirelessly from a source resonator; and

a load configured to consume the wireless power received from the source resonator,

wherein the wireless power receiving device reflects a portion of the wireless power received from the source resonator, and the target resonator is further configured to receive wireless power from the source resonator that has a change in impedance based on an impedance set value for a maximal power transmission and an impedance deviation corresponding to a frequency deviation between a resonance frequency and coupling frequency, wherein a source resonator and a target resonator are coupled at the coupling frequency,

wherein the coupling frequency is determined based on an amplitude of the reflected signal corresponding to a frequency band of the reflected signal,

wherein the impedance of the source resonator is adjusted by changing a distance between a conducting portion of the source resonator and a conductor of a matcher being electrically connected with the source resonator.

12. The wireless power receiving device of claim 11 , further comprising a rectifier to rectify a power signal received from the source resonator.