A non-contact power reception device includes a load such as a power storage device identified as a subject of power feeding, and a secondary self-resonant coil receiving electric power to be supplied to said load from an external primary self-resonant coil. The secondary self-resonant coil is configured so as to be switchable between a first state and a second state. The first state is selected in a power reception mode in which the secondary self-resonant coil is magnetically coupled with the primary self-resonant coil through resonance of a magnetic field. The second state is selected in a power non-reception mode in which the magnetic coupling of the secondary self-resonant coil with the primary self-resonant coil through resonance is weaker than in the first state.

A non-contact power reception device includes a load such as a power storage device identified as a subject of power feeding, and a secondary self-resonant coil receiving electric power to be supplied to said load from an external primary self-resonant coil. The secondary self-resonant coil is configured so as to be switchable between a first state and a second state. The first state is selected in a power reception mode in which the secondary self-resonant coil is magnetically coupled with the primary self-resonant coil through resonance of a magnetic field. The second state is selected in a power non-reception mode in which the magnetic coupling of the secondary self-resonant coil with the primary self-resonant coil through resonance is weaker than in the first state.

Cables (1, 2) comprise first and second conductors (1, 2) for transporting signals to be picked-up in contactless manners. At first/second locations (3, 4), the first and second conductors (1, 2) are at first/second distances from each other. The first locations (3) are neutral locations where the conductors (1, 2) are parallel. The second locations (4) are pick-up locations. The second distances are larger than the first distances. Pick-up devices for picking-up signals in a contactless manner from the cables (1, 2) comprise parts for defining minimum values of the second distances. These parts may comprise core-parts, such as center ends (10) of E-shaped magnetic cores further comprising outer ends (11, 12) and backs (13). Methods for installing pick-up devices comprise steps of at second locations (4) increasing a distance between the first and second conductors (1, 2) from a value of the first distance to a value of the second distance. Twin-cables (1, 2) or twin-lead-cables (1, 2) are suited well for allowing signals to be picked-up in contactless manners.

A power transmission device that wirelessly supplies power with a power receiving device includes a power transmission unit configured to wirelessly transmit power to a power receiving device, a receiving unit configured to receive a receiving power amount from the power receiving device, an evaluation unit configured to compare a reference value of the power receiving device and the receiving power amount and evaluate a transmission efficiency of power to the power receiving device based on a comparison result, and a transmission unit configured to transmit an evaluation result by the evaluation unit to the power receiving device.

A signal analysis circuit for a supplying-end module includes a first voltage divider circuit, for attenuating a coil signal of a supplying-end coil; a first amplifier circuit, for obtaining parts of the attenuated coil signal higher than a reference voltage to output a half-wave signal; a first envelope detector, for performing envelope extraction on the half-wave signal to obtain a DC signal; a second voltage divider circuit, for attenuating the half-wave signal; a second amplifier circuit, for obtaining parts of the attenuated half-wave signal higher than the DC signal to output an amplified half-wave signal; a second envelope detector, for performing envelope extraction on the amplified half-wave signal to generate an envelope signal; a coupling capacitor, for filtering out the DC component of the envelope signal; a third voltage divider circuit, for combining the AC component of the envelope signal with a DC voltage to retrieve a trigger signal.

There is provided a power feeding apparatus including a remaining battery level reception unit configured to receive a remaining battery level of a respective secondary battery included in a respective power receiving apparatus among a plurality of power receiving apparatuses from the respective power receiving apparatuses, a power feeding time determination unit configured to determine power feeding time for the power receiving apparatuses based on the remaining battery level, and a power feeding unit configured to wirelessly feed power to the power receiving apparatuses for the power feeding time.

Systems, methods and apparatus for wireless charging are disclosed. A charging device has a plurality of charging cells provided on a charging surface, a charging circuit and a controller. The controller may be configured to cause the charging circuit to provide a charging current to a resonant circuit when a receiving device is placed on the charging surface, detect a change or rate of change in voltage or current level associated with the resonant circuit, provide a measurement slot by terminating the charging current for a period of time, and determine that the receiving device has been removed from the charging surface by performing a passive or digital ping procedure during the measurement slot.

A power transfer unit configured to transfer power using magnetic fields, and a foreign object remover configured to remove a foreign object in the vicinity of a power transfer path when the power is transferred.

A power transmission device includes: a power supply circuit that generates an alternating voltage; a power transmission coil that receives an alternating voltage generated by the power supply circuit to thereby generate a magnetic field; a power transmission resonator that includes: a resonant coil; and a resonant capacitor and through which electromagnetic induction causes an electric current to flow when a magnetic field is generated by the power transmission coil to enter a resonance state; and a control circuit that controls the position or the orientation of the power transmission coil with respect to the power transmission resonator in the direction in which a standing wave ratio in a transmission line from the power supply circuit to the power transmission coil decreases.

Disclosed are low power electronic devices configured to exploit the sub-threshold swing, unidirectional tunneling, and low-voltage operation of steep slope-tunnel tunnel field-effect transistors (TFET) to improve power-conversion efficiency and power-efficiency of electrical systems incorporating the TFET as an electrical component to perform energy harvesting, signal processing, and related operations. The devices include a HTFET-based rectifier having various topologies, a HTFET-based DC-DC charge pump converter, a HTFET-based amplifier having an amplifier circuit including a telescopic operational transconductance amplifier, and a HTFET-based SAR A/D converter having a HTFET-based transmission gate DFF. Any one of the devices may be used to generate a RF-powered system with improved power conversion efficiencies of power harvesters and power efficiencies of processing components within the system.