The disclosure features apparatus, methods, and systems for wireless power transfer that include a power source featuring at least one resonator, a power receiver featuring at least one resonator, a first detector featuring one or more loops of conductive material and configured to generate an electrical signal based on a magnetic field between the power source and the power receiver, a second detector featuring conductive material, and control electronics coupled to the first and second detectors, where during operation, the control electronics are configured to measure the electrical signal of the first detector and compare the measured electrical signal of the first detector to baseline electrical information for the first detector to determine information about whether debris is positioned between the power source and the power receiver.

Provided is a wireless power transmission device to reduce an electromagnetic wave except for a signal to be transmitted during wireless power transmission, the wireless power transmission device including a transmitter configured to generate a magnetic field by inputting a high-frequency power signal generated by a transmission circuit into a first coil, a receiver configured to generate an induced current by allowing the generated magnetic field to pass through a second coil, and a reducer configured to reduce a harmonic component of the high-frequency power signal using a third coil inserted on a path between the transmitter and the receiver.

Provided is a wireless power transmission device to reduce an electromagnetic wave except for a signal to be transmitted during wireless power transmission, the wireless power transmission device including a transmitter configured to generate a magnetic field by inputting a high-frequency power signal generated by a transmission circuit into a first coil, a receiver configured to generate an induced current by allowing the generated magnetic field to pass through a second coil, and a reducer configured to reduce a harmonic component of the high-frequency power signal using a third coil inserted on a path between the transmitter and the receiver.

Systems and methods are described for a passive flux bridge for charging electric vehicles. These systems and methods include a mobile apparatus including mobility components and a material with high magnetic permeability and electrical resistivity. In aspects, the mobility components, e.g., wheels or continuous track, are configured to enable movement of the apparatus and positioning of the apparatus proximate to a vehicle power-transfer apparatus of an electric vehicle. The magnetically permeable and electrically resistive material, e.g., ferrite, is configured to passively channel magnetic flux between a base power-transfer system and the vehicle power-transfer system to wirelessly charge a battery of the electric vehicle.

In wireless system, radio frequency (RF) energy harvesting addresses the problem of limited battery lifetime in wireless nodes. In this invention, a wireless system for improving performance and prolonging battery life time of node, a battery assisted relay (2) framework is introduced. In this battery assisted relay framework, the energy harvested (EH) relay (2) augments the harvested energy with energy drawn from the battery (10) so as to prolong the battery life. Thus the following optimizations become relevant (i) maximizing throughput performance by using fixed small amount of battery energy in every signaling interval, (ii) minimizing battery energy consumption with predefined throughput performance requirement by optimizing a fixed charging time and energy together (best statistically optimum fixed charging time and energy drawn are determined), (iii) minimizing battery energy consumption by allowing channel-dependent energy harvesting duration, and (iv) minimizing battery energy consumption by drawing energy from the battery dependent on channel values. The suggested method and system can increase throughput as well as battery lifetimes, and are thus of practical value.

A power transmitting device transmits power tower power receiving device having a power receiving coil, in water. The power transmitting device includes one or more annular transmitting coils including a power transmitting coil configured to transmit the power to the power receiving coil via a magnetic field, a support member located in an inner space of the transmitting coil, which is formed by the annular transmitting coil, the support member including an outer periphery along an inner periphery of the annular transmitting coil, and supporting the transmitting coil from the inner space, a power transmitting unit configured to supply A/C power to the power transmitting coil, and a capacitor connected to the transmitting coil, and forming a resonance circuit resonating together with the transmitting coil.

A power transmitting device transmits power tower power receiving device having a power receiving coil, in water. The power transmitting device includes one or more annular transmitting coils including a power transmitting coil configured to transmit the power to the power receiving coil via a magnetic field, a support member located in an inner space of the transmitting coil, which is formed by the annular transmitting coil, the support member including an outer periphery along an inner periphery of the annular transmitting coil, and supporting the transmitting coil from the inner space, a power transmitting unit configured to supply A/C power to the power transmitting coil, and a capacitor connected to the transmitting coil, and forming a resonance circuit resonating together with the transmitting coil.

In a first radio frequency (RF) device, circuits determine a non-line-of-sight (NLOS) radio path, and select a first plurality of reflector devices associated with the NLOS radio path from a second plurality of reflector devices. The first plurality of reflector devices, are selected based on a first set of criteria, includes an active reflector device and a passive reflector device, and are controlled to transmit a plurality of RF signals to a second RF device based on a second set of criteria. The second RF device is associated with electronic devices. The first RF signal interferes with a second RF signal of the RF signals. A first type of signal associated with the plurality of RF signals is converted to a second type of signal at the second RF device, and the second type of signal is transmitted by the second RF device to the one or more electronic devices.

In a first radio frequency (RF) device, circuits determine a non-line-of-sight (NLOS) radio path, and select a first plurality of reflector devices associated with the NLOS radio path from a second plurality of reflector devices. The first plurality of reflector devices, are selected based on a first set of criteria, includes an active reflector device and a passive reflector device, and are controlled to transmit a plurality of RF signals to a second RF device based on a second set of criteria. The second RF device is associated with electronic devices. The first RF signal interferes with a second RF signal of the RF signals. A first type of signal associated with the plurality of RF signals is converted to a second type of signal at the second RF device, and the second type of signal is transmitted by the second RF device to the one or more electronic devices.

Wireless power receivers are described, which are used in conjunction with a wireless power transmission system. For instance, a wireless power receiver is provided comprising an antenna configured to receive wireless power signals from a wireless power signal transmitter. The antenna can be coupled to wireless power circuitry that delivers power based on the wireless power signals received by the antenna. Further, a module is provided that contains the wireless power receiver and couples to a device powered by the wireless power circuitry. Further, the module is configured to couple to the device in a fixed position that affixes an orientation of the antenna relative to the device.