A wireless power feed system with high transfer efficiency of electric power is disclosed. The wireless power feed system includes a power feeding device and a power receiving device, wherein the power feeding device includes a first electromagnetic coupling coil that is connected to an AC power source via a directional coupler; a first resonant coil; a switch connected to the opposite ends of the first resonant coil; a control circuit which conducts switching on/off of the switch based on a parameter of an amplitude of a reflective wave detected by the directional coupler; and an analog-digital converter provided between the first electromagnetic coupling coil and the control circuit; and the power receiving device includes a second resonant coil; and a second electromagnetic coupling coil, and wherein the first electromagnetic coupling coil is provided between the first resonant coil and the second resonant coil.

A battery case has first and second coils on opposing sides of a battery and has switching circuitry that is coupled between the first and second coils. The battery case has a battery that provides supplemental battery power wirelessly to a wireless power receiving device via the second coil when the switching circuitry is in an open state. The case can also receive power wirelessly with the first coil from a wireless charging mat when the switching circuitry is in the open state. In a closed state, the switching circuitry shorts the first and second coils together so that current flowing through the first coil flows through the second coil in series and so that wireless power from the wireless charging mat that is received with the first coil is transmitted wirelessly to the wireless power receiving device using the second coil.

A resonator is provided. The resonator comprises at least two inductors and at least four capacitive electrodes electrically connected to the inductors. The capacitive electrodes and the inductors are configured to resonate and generate or couple with an electric field. The electrodes have either four fold mirror or rotational symmetry.

An electronic device and method for transmitting and receiving a wireless power are provided. An electronic device for transmitting and receiving wireless power may include a resonator configured to operate, based on a plurality of operating modes of the electronic device including a power reception mode, a relay mode, and a power transmission mode, wherein: (i) in the power reception mode, the resonator is configured to receive power from a wireless power transmitter, (ii) in the relay mode, the resonator is configured to relay power received from the wireless power transmitter to a wireless power receiver, and (iii) in the power transmission mode, the resonator is configured to transmit power to the wireless power receiver; and a path controller configured to control at least one electrical pathway of electronic device based on the operating mode.

A wireless power transmission system includes a transmission antenna that has a source antenna coil and an internal repeater coil. The system further includes two demodulation circuits, for demodulating incoming communications from a power receiver. One demodulation circuit receives sensed signals at the source coil and the other receives sensed signals at the internal repeater coil. The pair of sensed signals are then summed at a summing amplifier to generate a communications signal for input to a controller of the wireless power transmission system.

Provided is an amplifying repeater to intensify and amplify a magnetic field of electromagnetic waves. Also provided is a wireless power conversion charging device using the magnetic field of electromagnetic waves, which is located between an electromagnetic wave generating source transmitter and a receiving coil or attached to a transmitter and a receiving coil. Accordingly, charging power for various electronic devices can be provided and power can be wirelessly supplied to various loads.

A wireless charging apparatus for a wireless power transmission system. The apparatus includes a voltage conversion circuit, an excitation coil, n first resonance coils, and a controller, where n is greater than or equal to 3. The voltage conversion circuit is connected to the excitation coil and converts a power grid voltage into a high-frequency alternating current voltage. The excitation coil generates a magnetic field based on the high-frequency alternating current voltage. The n first resonance coils are arranged in different directions and conducts the magnetic field, and the controller monitors power statuses of the first resonance coils, and enable or disable the first resonance coils based on the power statuses.

Disclosed herein is a wireless charging apparatus for preventing cancelation of magnetic fields generated between a plurality of adjacent transmission coils by placing a repeater on the plurality of transmission coils, the wireless charging apparatus including a plurality of transmission coils spaced the same distance apart from a reference point, and a repeater placed on the plurality of transmission coils to be overlapped with each of the plurality of transmission coils with respect to the reference point that is a center, wherein a coupling coefficient between each of the plurality of transmission coils and the repeater is higher than a coupling coefficient between the plurality of transmission coils.

A foreign matter detecting device includes a plurality of detection coils disposed so as to be capable of being electromagnetically coupled to each other between a transmission coil of a power transmission device and a reception coil of a power reception device between which power is transmitted in a non-contact manner, a plurality of capacitors each forming a resonance circuit together with each of the plurality of detection coils, a power supply circuit supplying AC power having a predetermined frequency to an input coil that is one of the plurality of detection coils, and a detection circuit detecting a voltage of AC power transmitted via the plurality of detection coils from an output coil that one of the plurality of detection coils and is different from the input coil, and detecting foreign matter entrapped between the transmission coil and the reception coil according to the voltage detected.

Disclosed are various embodiments relating to a wearable device. According to an embodiment, a wearable device including a wireless charging device may include: a housing of the wearable device; first and second straps connected to the housing; first and second buckles provided on the first and second straps; a reception resonator provided in the housing to receive power transmitted from the outside; and a wireless power reception module provided in the housing and electrically connected to the reception resonator. Various other embodiments can be made.