Apparatus and method for wireless power transmission

1. A wireless power transmitter comprising:

a source resonator configured to wirelessly transmit power to a target device;

at least one sub-resonator positioned inside of the source resonator; and

a controller configured to determine a direction of current flowing in the at least one sub-resonator based on a radio between a resonance frequency of the source resonator and a resonance frequency of the at least one sub-resonator,

wherein a distribution of a magnetic field is controlled based on the direction.

2. The wireless power transmitter of claim 1 , wherein the source resonator comprises:

a first transmission line comprising a first signal conducting portion, a second signal conducting portion, and a first ground conducting portion, the first ground conducting portion corresponding to the first signal conducting portion and the second signal conducting portion;

a first conductor electrically connecting the first signal conducting portion to the first ground conducting portion;

a second conductor electrically connecting the second signal conducting portion to the first ground conducting portion; and

at least one first capacitor inserted between the first signal conducting portion and the second signal conducting portion, in series with respect to current flowing through the first signal conducting portion and the second signal conducting portion.

3. The wireless power transmitter of claim 2 , wherein the first transmission line, the first conductor, and the second conductor form a loop structure.

4. The wireless power transmitter of claim 3 , further comprising:

a matcher configured to determine an impedance of the source resonator, the matcher being located within the loop structure.

5. The wireless power transmitter of claim 1 , wherein the controller controls the resonance frequency of the at least one sub-resonator to have a value greater than the resonance frequency of the source resonator, so that the strength of the magnetic field within the at least one sub-resonator is increased and the strength of the magnetic field in a region between the at least one sub-resonator and the source resonator is reduced.

6. The wireless power transmitter of claim 1 , wherein the controller controls the resonance frequency of the at least one sub-resonator to have a value less than the resonance frequency of the source resonator, so that the strength of the magnetic field within the at least one sub-resonator is reduced and the strength of the magnetic field in a region between the at least one sub-resonator and the source resonator is increased.

7. The wireless power transmitter of claim 1 , wherein the controller controls one or more resonance frequencies of a plurality of sub-resonators located in a predetermined area within the source resonator to have values less than or greater than the resonance frequency of the source resonator, and controls the strength of the magnetic field within one or more of the plurality of sub-resonators, and the strength of the magnetic field in a region between the source resonator and one or more of the plurality of sub-resonators.

8. The wireless power transmitter of claim 1 , wherein the source resonator comprises a spiral resonator formed by winding a coil in a spiral shape.

9. The wireless power transmitter of claim 1 , wherein the at least one sub-resonator comprises:

a second transmission line comprising a third signal conducting portion, a fourth signal conducting portion, and a second ground conducting portion, the second ground conducting portion corresponding to the third signal conducting portion and the fourth signal conducting portion;

a third conductor electrically connecting the third signal conducting portion to the second ground conducting portion;

a fourth conductor electrically connecting the fourth signal conducting portion to the second ground conducting portion; and

at least one second capacitor inserted between the third signal conducting portion and the fourth signal conducting portion, in series with respect to current flowing through the third signal conducting portion and the fourth signal conducting portion.

10. The wireless power transmitter of claim 9 , wherein the controller controls the resonance frequency of the at least one sub-resonator, by controlling a capacitance of the at least one second capacitor, or the length, the width, or both of the second transmission line.

11. The wireless power transmitter of claim 9 , wherein the second transmission line, the third conductor, and the fourth conductor form a rectangular loop structure.

12. The wireless power transmitter of claim 9 , wherein the second transmission line, the third conductor, and the fourth conductor form a circular loop structure.

13. The wireless power transmitter of claim 9 , wherein the second transmission line, the third conductor, and the fourth conductor form a cross-shaped loop structure.

14. The wireless power transmitter of claim 1 , wherein the at least one sub-resonator comprises at least one sub-sub-resonator that is located within the at least one sub-resonator that is configured to support the at least one sub-resonator and to increase or reduce the strength of the magnetic field when the power is wirelessly transmitted.

15. The wireless power transmitter of claim 1 , wherein the at least one sub-resonator comprises a meta-resonator, a spiral resonator, or a helical resonator.

16. A wireless power transmission method comprising:

wirelessly transmitting power to a target device via a source resonator;

determining a direction of current flowing in at least one sub-resonator based on a ratio between a resonance frequency of the source resonator and a resonance frequency of the at least one sub-resonator, the at least one sub-resonator positioned inside of the source resonator,

wherein a distribution of a magnetic field is controlled based on the direction.

17. The wireless power transmission method of claim 16 , wherein the controlling comprises controlling the resonance frequency of the at least one sub-resonator to have a value greater than the resonance frequency of the source resonator, so that the strength of the magnetic field formed in the at least one sub-resonator is increased and the strength of the magnetic field formed between the at least one sub-resonator and the source resonator is reduced.

18. The wireless power transmission method of claim 16 , wherein the controlling comprises controlling the resonance frequency of the at least one sub-resonator to have a value less than the resonance frequency of the source resonator, so that the strength of the magnetic field formed in the at least one sub-resonator is reduced and the strength of the magnetic field formed between the at least one sub-resonator and the source resonator is increased.

19. The wireless power transmission method of claim 16 , wherein the controlling comprises controlling one or more of resonance frequencies of a plurality of sub-resonators located in a predetermined area within the source resonator to have values less than or greater than the resonance frequency of the source resonator, and controlling the strength of the magnetic field within one or more of the plurality of sub-resonators, and the strength of the magnetic field in a region between the source resonator and one or more of the plurality of sub-resonators.

20. The wireless power transmission method of claim 16 , wherein the controlling comprises controlling the resonance frequency of the at least one sub-resonator, by controlling a capacitance of at least one capacitor, or the length, the width, or both, of a transmission line.