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.

In some embodiments, the instant invention involves an electrical system that at least includes: a three-phase inductor, including: a core, including: a plurality of core lamination pieces. having: a first core lamination piece and a second core lamination piece; where the first core lamination piece includes a plurality of first laminations that have a first shape and arranged in a first pattern to form a plurality of first differential mode gaps; where the second core lamination piece includes a plurality of second laminations that have a second shape and arranged a second pattern to form a plurality of second differential mode gaps; where the first pattern and the second pattern are distinct; where the first core lamination piece and the second core lamination piece are positioned at a particular orientation of the first pattern to the second pattern so that to increase a common mode inductance of the core.

A wireless power transmission system is disclosed. In one aspect, the system includes a transmitting antenna configured to transmit power, via a magnetic field, to a receiving antenna to power a load. The system also includes a tuning loop electrically isolated from the transmitting antenna and being movable relative to the transmitting antenna to adjust a coupling between the transmitting antenna and the tuning loop.

A wireless power transmission apparatus includes: a transmitter that wirelessly transmits electric power; and a receiver that can receive, in a resonant relation with the transmitter, a transmission signal including the electric power transmitted from the transmitter, wherein the receiver includes a frequency variable unit that can change a reception resonant frequency; a detecting unit that detects reception power; and a control unit that controls the frequency variable unit to perform frequency adjustment such that the reception power detected by the detecting unit is maximized.

A power transmission device includes: a transmission means including at least an oscillation means and a resonant means and for transmitting power to a power reception device by using a magnetic resonance-type power transmission technique; and a control means for controlling the reception power of the power reception device so as to be at a maximum by changing at least one of an oscillation frequency of the oscillation means and a resonant frequency of the resonant means.

A reactor 1 according to the present invention includes a coil 2 and a magnetic core 3 where the coil 2 is disposed. In the reactor 1, a core part 4A (4B) including a stacked columnar body having a plurality of core pieces 31m and a plurality of gap members 31g stacked and coating resin 5A (5B) in which a peripheral surface coating portion 51oA (51oB) for coating an outer peripheral surface of the stacked columnar body to integrally hold the core piece 31m and the gap member 31g and an end surface coating portion 51eA for coating one end surface of the stacked columnar body are molded integrally is used for a part of the magnetic core 3, that is, an inner core 31. A manufacturing error of the core piece 31m or the gap member 31g is absorbed by the end surface coating portion 51eA. Consequently, the core part 4A (4B) can be molded with high accuracy and an outer core 32 can be assembled properly. Thus, the reactor 1 has high assembling workability.

A reactor 1 according to the present invention includes a coil 2 and a magnetic core 3 where the coil 2 is disposed. In the reactor 1, a core part 4A (4B) including a stacked columnar body having a plurality of core pieces 31m and a plurality of gap members 31g stacked and coating resin 5A (5B) in which a peripheral surface coating portion 51oA (51oB) for coating an outer peripheral surface of the stacked columnar body to integrally hold the core piece 31m and the gap member 31g and an end surface coating portion 51eA for coating one end surface of the stacked columnar body are molded integrally is used for a part of the magnetic core 3, that is, an inner core 31. A manufacturing error of the core piece 31m or the gap member 31g is absorbed by the end surface coating portion 51eA. Consequently, the core part 4A (4B) can be molded with high accuracy and an outer core 32 can be assembled properly. Thus, the reactor 1 has high assembling workability.

A reactor includes an annular iron core and four coils separately wound around the iron core. The four coils have first electrodes connected to output terminals of four choppers, respectively, and second electrodes each connected to a load. Therefore, the four choppers can be connected in parallel to the load by one reactor.

A reactor includes an annular iron core and four coils separately wound around the iron core. The four coils have first electrodes connected to output terminals of four choppers, respectively, and second electrodes each connected to a load. Therefore, the four choppers can be connected in parallel to the load by one reactor.