Abstract: A wireless power transmission system, and an apparatus and method for controlling power in the wireless power transmission system are provided. The method includes determining a resonance frequency of the wireless power transmission system in which a wireless power transmission efficiency is greater than or equal to a predetermined value. The method further includes generating an operation power based on the wireless power transmission efficiency, the operation power being used to operate a target device. The method further includes transmitting the operation power to the target device. The method further includes controlling an amount of the operation power received by the target device to be within a predetermined range.

Abstract: A communication method in a wireless power transmission system includes detecting state information of a plurality of channels available in a communication cell when all of the plurality of channels have already been respectively assigned to a plurality of sources configured to transmit wireless power respectively, determining a channel to be used for communication based on the state information, determining whether the determined channel is being used by a respective one of the plurality of sources to which the determined channel has already been assigned, and determining whether the determined channel is to be used for communication based on a result of the determination of whether the determined channel is being used.

Abstract: A resonate power generator is provided. The resonate power generator may include a waveform and sequence memory to record a predetermined waveform and a predetermined sequence, a delta-sigma modulator to delta-sigma modulate an output signal of the waveform and sequence memory, and a waveform recovery unit to receive, as an input, an output radio frequency (RF) signal of the delta-sigma modulator, and to convert the input into a waveform in a form of an impulse.

Abstract: A load impedance decision device, a wireless power transmission device, and a wireless power transmission method are provided. At least one of a distance and an angle between two resonators may be measured. A load impedance may be determined based on at least one of the measured distance and the measured angle. When the distance between the two resonators changes, a high power transfer efficiency may be maintained without using a separate matching circuit. Where the load impedance is determined, a test power may be transmitted. Depending on a power transfer efficiency of the test power, the load impedance may be controlled and power may be wirelessly transmitted from the source resonator to the target resonator.

Abstract: A method and apparatus to detect load fluctuation of a wireless power transmission are provided. A wireless power transmitter includes a resonator configured to wirelessly transmit, to a target device, an output power. The wireless power transmitter further includes a power detector configured to detect a current of the output power. The wireless power transmitter further includes a controller configured to detect a change in the current, and to detect a target load based on the change in the current. The target load includes a load of which the output power is applied thereto.

Abstract: Provided are methods and apparatuses for distributing wireless power in a wireless power transmission system. According to a general aspect, a source device that distributes a wireless power in a wireless power transmission system may include: a matching circuit searching unit configured to determine information associated with a matching circuit of a source device based on one or more target devices and the amount of power to be distributed to the one or more of the target devices; and a matching circuit modifying unit configured to modify the shape of the matching circuit of the source device to correspond to the determined information associated with the matching circuit of the source device.

Abstract: An apparatus and method are described that may enable a target device to communicate with a source device using a wireless power. The communication apparatus receives a wireless power from a source resonator through a magnetic coupling between the source resonator and a target resonator. The communication apparatus transmits a message, and modulates the message based on the received wireless power and impedance mismatch between the source device and the target device. The communication apparatus controls the impedance mismatch by changing an impedance of the target device.

Abstract: An apparatus and method for communication using a wireless power are provided. The apparatus includes an amplifier configured to amplify an input signal based on a power supplied to the amplifier. The apparatus further includes a control unit configured to detect a change in an impedance of a target device, and to change the power based on the change in the impedance. The apparatus further includes a demodulation unit configured to receive a message from the target device, and to demodulate the message based on the changed power.

Abstract: A wireless power transmission and charging system, and a power control method of the wireless power transmission and charging system are provided. The power control method may include generating charging power using the power amplifier. The charging power may be used to charge a target device. The charging power may be transmitted to the target device. The voltage supplied to the power amplifier may be adjusted based on a detected change in the current input to the power amplifier, a detected change in the temperature of the source device, a detected change in the amount of the power received to the target device, or a detected change in the temperature of the target device.

Abstract: An apparatus for transmitting a high efficiency variable power includes a pulse generating unit configured to generate a pulse signal comprising a pulse having a duration corresponding to an amount of power transmitted; a pulse stream generating unit configured to convert the pulse signal to a pulse stream having pulse shape corresponding to the duration of the pulse and data to be transmitted; and a high frequency modulating unit configured to output a variable power by modulating a high frequency signal having a constant amplitude on a time axis by repeatedly outputting and not outputting the high frequency signal based on the pulse stream.

Abstract: An apparatus and method of protecting a power receiver of a wireless power transmission system are provided. A wireless power receiver includes a rectifier comprising an input and an output, and configured to receive a signal through the input, to rectify the signal to produce a rectified signal, and to output the rectified signal through the output, and a capacitor connected to the output of the rectifier and to ground. The wireless power receiver further includes a direct current-to-direct current (DC/DC) converter connected to the output of the rectifier and to a load, and configured to convert the rectified signal to a power, and to provide the power to the load, and a device configured to create a short circuit to protect the rectifier and/or the capacitor when a voltage greater than a threshold voltage is applied to the input of the rectifier and/or the output of the rectifier.

Abstract: An overvoltage protecting unit and an overcurrent protecting unit protect a power device from an overvoltage and an overcurrent using a comparator having hysteresis. An overtemperature protecting unit protects the power device from an overtemperature using a thermistor having a resistance that changes as a temperature of the thermistor changes.

Abstract: An apparatus and method for efficiently, wirelessly transmitting a power to a plurality of target devices are provided. A wireless power transmitter may include: a source resonator configured to wirelessly transmit energy to a target device with at least one target resonator, the energy being stored in a capacitor; and a feeding unit configured to generate an induced current flowing in the source resonator in the same direction as a direction of an input current flowing in a transmission line, the feeding unit being electrically connected to the capacitor and forming a closed loop with the source resonator.

Abstract: A rectifier is provided. The rectifier includes a first rectification unit having an anode connecting to a negative radio frequency (RF) port and a cathode connecting to a positive direct current (DC) port, a second rectification unit having an anode connecting to a positive RF port and a cathode connecting to the positive DC port, a third rectification unit having an anode connecting to a ground and a cathode connecting to the negative RF port, and a fourth rectification unit having an anode connecting to the ground and a cathode connecting to the positive RF port. The first rectification unit includes a plurality of first diodes that are connected in parallel, and the second rectification unit includes a plurality of second diodes that are connected in parallel.

Abstract: An apparatus and method of using near field communication (NFC) and wireless power transmission (WPT) are provided. A power receiving apparatus includes a resonator configured to receive a power and to output the power. The power receiving apparatus further includes a near field communication (NFC) receiver configured to perform wireless communication using the power output by the resonator. The power receiving apparatus further includes a wireless power transmission (WPT) receiver configured to supply a voltage using the power output by the resonator. The power receiving apparatus further includes a connecting unit configured to selectively connect the resonator to either the NFC receiver or the WPT receiver. The power receiving apparatus further includes a mode selector configured to control the connecting unit to selectively connect the resonator to either the NFC receiver or the WPT receiver based on the power output by the resonator.

Abstract: An apparatus and method for controlling a magnetic field when power is wirelessly transmitted are provided. According to one general aspect, a wireless power transmitter may include: a source resonator configured to wirelessly transmit power to a target device including at least one sub-resonator located there within; and a magnetic field distribution controller configured to control the distribution of the magnetic field within the resonator based the resonance frequency of the at least one sub-resonator and the resonance frequency of the source resonator.

Abstract: Disclosed is a resonator for wireless power transmission used in a mobile device. The resonator includes a substrate, at least one microstrip line, and a magnetic core. The microstrip line is formed on the substrate and is provided at one side thereof with a slit to have an open-loop shape. The magnetic core is formed on the substrate and is disposed on a space defined by the microstrip line to increase coupling strength.

Abstract: A high efficiency variable power transmitting apparatus outputs a variable power by modulating, with respect to a time axis, a high frequency signal having a constant amplitude by turning the high frequency signal ON and OFF, amplifying the variable power to satisfy a requested power level of a target device based on a supply voltage having a predetermined level, converting an alternating current (AC) voltage received from a power source to a direct current (DC) voltage, generating the supply voltage having the predetermined level based on the DC voltage, and providing the supply voltage having the predetermined level to the PA.

Abstract: Provided is a wireless power resonator. The wireless power resonator may include a transmission line and a capacitor, may form a loop structure, and may further include a matcher to determine an impedance of the wireless power resonator.

Abstract: Provided are a transmission system and a wireless power transmission and reception controlling method. According to an embodiment, a wireless power receiver may include: a target communication unit configured to receive, from a wireless power transmitter, a wake-up request signal and synchronization information with respect to wireless power transmission, and to transmit a response signal with respect to the wake-up request signal to the wireless power transmitter; a load path switch configured to activate based on timing information included in the synchronization information; and a target resonator configured to receive wireless power from a source resonator of the wireless power transmitter, when the load path switch is activated.