Apparatus and method for resonance in wireless power transmission system
A resonant apparatus in a wireless power transmission system, includes a main resonant unit configured to form magnetic resonant coupling between the resonant apparatus and a resonator. The resonant apparatus further includes a field guiding resonant unit configured to focus a magnetic field on an internal portion of the main resonant unit, and a field additive resonant unit configured to adjust a magnitude of a magnetic field formed between the main resonant unit and the field guiding resonant unit.
1. A resonant apparatus in a wireless power transmission system, the resonant apparatus comprising:
a main resonator configured to form magnetic resonant coupling between the resonant apparatus and a target resonator of a wireless power receiver;
a field guiding resonant unit configured to focus a magnetic field on an internal portion of the main resonator;
a field additive resonant unit configured to adjust a magnitude of a magnetic field formed between the main resonator and the field guiding resonant unit, and comprising a plurality of sub-resonant units; and
a controller is configured to:
receive state information from the wireless power receiver,
detect a reflected wave of a charging power and misalignment between the main resonator and the target resonator based on the detected reflected wave, and
control two or more of the plurality of sub-resonant units to be turned ON or OFF, based on the detected misalignment and/or the received state information, wherein the controller turns ON one or more sub-resonant units, among the sub-resonant units, disposed in a portion in which the resonant apparatus overlaps the target resonator, and turn OFF a remained of the sub-resonant units,
wherein the state information includes efficiency information of power transmission and the efficiency information is calculated based on a ratio of an amount of received power to an amount of transmitted power.
2. The resonant apparatus of claim 1 , wherein:
the field guiding resonant unit is disposed in the internal portion of the main resonant unit; and
the field additive resonant unit is disposed between the main resonant unit and the field guiding resonant unit.
3. The resonant apparatus of claim 1 , wherein a resonant frequency of the field guiding resonant unit is controlled by a controller.
4. The resonant apparatus of claim 1 , wherein a resonant frequency of the field guiding resonant unit is greater than or equal to an operating frequency of the resonant apparatus.
5. The resonant apparatus of claim 1 , wherein each of the sub-resonant units comprises a capacitor and a switch connected in parallel to the capacitor.
6. The resonant apparatus of claim 1 , wherein each of the main resonant unit and the field guiding resonant unit comprises a circular loop or a rectangular loop.
7. The resonant apparatus of claim 1 , wherein the field additive resonant unit comprises circular loop conductors connected to the main resonant unit.
8. The resonant apparatus of claim 1 , wherein:
the field guiding resonant unit and the field additive resonant unit comprises a loop in which ends of the field guiding resonant unit are connected to ends of the field additive resonant unit; and
a width of the field guiding resonant unit is narrower than a width of the field additive resonant unit.