Abstract: Various embodiments for controlling a resonant frequency of a resonator are described. A system includes at least one resonant circuit and an active variable reactance circuit that controls a resonant frequency of the at least one resonant circuit. The active variable reactance circuit includes an electrically-controllable switching element and a switch controller sub-circuit configured to switch the electrically-controllable switching element at a frequency of a radio-frequency (RF) current or voltage passing through or across a device such that the RF current flowing from a first terminal to a second terminal is substantially sinusoidal.

Abstract: An accessory for charging or powering an electronic device is described. The accessory may include a wireless power receiver configured to receive power while the case is positioned in a first wireless power transfer area. The accessory may further include a wireless power transmitter electrically coupled to the wireless power receiver. The wireless power transmitter is configured to power the electronic device through a second wireless power transfer area, which may be smaller than the first wireless power transfer area. The wireless power transmitter may include a QI standard-compliant wireless power transmitter.

Abstract: Disclosed is an apparatus for use in wireless energy transfer, which includes a first resonator structure configured to transfer energy non-radiatively with a second resonator structure over a distance greater than a characteristic size of the second resonator structure. The non-radiative energy transfer is mediated by a coupling of a resonant field evanescent tail of the first resonator structure and a resonant field evanescent tail of the second resonator structure.

Abstract: Various embodiments for tuning systems of coupled resonators are described to achieve a desired arrangement of RF current magnitudes and directions, and with a coupled resonant eigenfrequency equal to the desired driving frequency.

Abstract: A distributed radio frequency (RF) generator for wireless power transfer for wireless power transfer is described. A distributed RF generator can include an electrically-conductive loop having at least a first end and a second end that are adapted to be electrically coupled to one or more direct current (DC) power sources, where the loop comprises a plurality of segments, each of the plurality of segments comprising: a length of wire and at least one active component, wherein the at least one active component has a first terminal and a second terminal that are electrically coupled to the loop, wherein: a DC voltage exists between the first terminal and the second terminal; a DC current flows into the first terminal and out of the second terminal; an oscillating RF voltage is output across the first terminal and the second terminal; and the at least one active component is synchronized in phase.

Abstract: A tile is provided with built in wireless power transfer technology that enables power to be wirelessly transferred from a wireless power transfer resonator of the tile to a wireless power receiver device of the tile. The wireless power receiver device includes, or is electrically coupled to, one or more electrical devices disposed on a front surface of the tile that are to be power by the receiver device. An array of the tiles may be provided in which case each tile has a wireless power transfer resonator. At least one of the tiles of the array is electrically coupled to an RF power source. The EM field generated by each tile is inductively coupled from that tile to a nearest-neighbor tile of the array.

Abstract: A wireless power receiver circuit and method for use in a wireless power transfer system are provided for providing a constant current and voltage to an electrical load, such as a chemical cell device. A wireless power receiver circuit include a first comparator circuit and a second comparator circuit configured to receive output signals output from the DC load circuit, compare the received output signal with a preselected reference voltage signal, and output first and second sub-control signals, respectively. A logical gate may generate a control signal based on a comparison of the first sub-control signal and the second sub-control signal, and feed the control signal back to a resonator circuit to control a state of an electrically-controllable switch.

Abstract: A distributed radio frequency (RF) generator for wireless power transfer for wireless power transfer is described. A distributed RF generator can include an electrically-conductive loop having at least a first end and a second end that are adapted to be electrically coupled to one or more direct current (DC) power sources, where the loop comprises a plurality of segments, each of the plurality of segments comprising: a length of wire and at least one active component, wherein the at least one active component has a first terminal and a second terminal that are electrically coupled to the loop, wherein: a DC voltage exists between the first terminal and the second terminal; a DC current flows into the first terminal and out of the second terminal; an oscillating RF voltage is output across the first terminal and the second terminal; and the at least one active component is synchronized in phase.

Abstract: A tile is provided with built in wireless power transfer technology that enables power to be wirelessly transferred from a wireless power transfer resonator of the tile to a wireless power receiver device of the tile. The wireless power receiver device includes, or is electrically coupled to, one or more electrical devices disposed on a front surface of the tile that are to be power by the receiver device. An array of the tiles may be provided in which case each tile has a wireless power transfer resonator. At least one of the tiles of the array is electrically coupled to an RF power source. The EM field generated by each tile is inductively coupled from that tile to a nearest-neighbor tile of the array.

Abstract: A wireless power receiver is described that receives power wirelessly from a transmitter coil that generates an oscillating magnetic field. The wireless power receiver includes a receiving coil circuit having a diode string formed by an outer wire, an inner wire, and diodes. Each of the diodes include a first end coupled to the outer wire and a second end coupled to the inner wire such that each of the diodes are connected in parallel with one another. A rectifier circuit is coupled to ends of the diode string. The rectifier circuit includes capacitors and rectifying diodes, where at least one of the capacitors is configured to bring the diode string into resonance with the oscillating magnetic field. The rectifying diodes rectify the induced oscillating voltage to produce a DC voltage difference between the outer wire and the inner wire, thereby powering the diodes.

Abstract: A wireless power receiver circuit and method for use in a wireless power transfer system are provided for providing a constant current and voltage to an electrical load, such as a chemical cell device. A wireless power receiver circuit include a first comparator circuit and a second comparator circuit configured to receive output signals output from the DC load circuit, compare the received output signal with a preselected reference voltage signal, and output first and second sub-control signals, respectively. A logical gate may generate a control signal based on a comparison of the first sub-control signal and the second sub-control signal, and feed the control signal back to a resonator circuit to control a state of an electrically-controllable switch.

Abstract: A method and system for wireless power transfer are provided. The method includes adapting first and second variable form factor transmitters into at least first and second sets of cross-coupled segments, respectively, disposed about a pre-determined wireless power transfer area and spatially offset from one another by a preselected spatial offset that minimizes inductive coupling between the first and second sets of cross-coupled segments, transmitting, from first and second radio frequency (RF) power sources electrically coupled to the first and second sets of cross-coupled segments, respectively, RF power across the pre-determined wireless power transfer area via near electromagnetic fields of the variable form factor transmitters such that a magnetic field associated with the near electromagnetic fields rotates in a pattern having a preselected shape.

Abstract: Disclosed is an apparatus for use in wireless energy transfer, which includes a first resonator structure configured to transfer energy non-radiatively with a second resonator structure over a distance greater than a characteristic size of the second resonator structure. The non-radiative energy transfer is mediated by a coupling of a resonant field evanescent tail of the first resonator structure and a resonant field evanescent tail of the second resonator structure.

Abstract: A method for wireless power transfer. The method includes adapting a variable form factor transmitter into at least a plurality of cross-coupled segments disposed about a pre-determined wireless power transfer area, wherein the pre-determined wireless power transfer area comprises a dimension exceeding a wavelength corresponding to a characteristic frequency of the variable form factor transmitter, transmitting, from a radio frequency (RF) power source and based at least in part on the characteristic frequency, RF power across the pre-determined wireless power transfer area via a near electromagnetic field of the variable form factor transmitter, and reducing, based on opposing directions of magnetic fields induced by adjacent cross-coupled segments of the plurality of cross-coupled segments, a radiation loss of the wireless power transfer due to a far electromagnetic field of the variable form factor transmitter.

Abstract: Wireless power receiver circuits and methods for use in wireless power transfer systems are provided for providing a constant current or voltage, depending on which is needed, to an electrical load. The wireless power receiver circuits are configured to shut down the resonant responses of the receiver circuits when electrical power is not needed by the load to reduce power consumption and avoid unnecessary heat dissipation. Additionally, a switching device of the wireless power receiver circuit that is used for shutting down the resonant response can operate at relatively low frequencies, and consequently, can be implemented using relatively low-speed, relatively inexpensive components.

Abstract: A radio frequency (RF) power source for use with a wireless power transmitter is provided. A direct current (DC) voltage supply of the RF power source supplies a substantially constant DC voltage to RF power source circuitry of the RF power source. A first node of the RF power source circuitry is electrically coupled to a first terminal of the DC voltage supply. The RF power source circuitry has first and second terminals that are electrically coupled to first and second terminals, respectively, of a resonant magnetic loop antenna of the wireless power transmitter circuit to provide an RF current having a constant amplitude to the resonant magnetic loop antenna.

Abstract: A wireless power receiver is described that receives power wirelessly from a transmitter coil that generates an oscillating magnetic field. The wireless power receiver includes a receiving coil circuit having a diode string formed by an outer wire, an inner wire, and diodes. Each of the diodes include a first end coupled to the outer wire and a second end coupled to the inner wire such that each of the diodes are connected in parallel with one another. A rectifier circuit is coupled to ends of the diode string. The rectifier circuit includes capacitors and rectifying diodes, where at least one of the capacitors is configured to bring the diode string into resonance with the oscillating magnetic field. The rectifying diodes rectify the induced oscillating voltage to produce a DC voltage difference between the outer wire and the inner wire, thereby powering the diodes.

Abstract: A method for wireless power transfer. The method includes adapting a variable form factor transmitter into at least a plurality of cross-coupled segments disposed about a pre-determined wireless power transfer area, wherein the pre-determined wireless power transfer area comprises a dimension exceeding a wavelength corresponding to a characteristic frequency of the variable form factor transmitter, transmitting, from a radio frequency (RF) power source and based at least in part on the characteristic frequency, RF power across the pre-determined wireless power transfer area via a near electromagnetic field of the variable form factor transmitter, and reducing, based on opposing directions of magnetic fields induced by adjacent cross-coupled segments of the plurality of cross-coupled segments, a radiation loss of the wireless power transfer due to a far electromagnetic field of the variable form factor transmitter.

Abstract: A method and system for wireless power transfer are provided. The method includes adapting first and second variable form factor transmitters into at least first and second sets of cross-coupled segments, respectively, disposed about a pre-determined wireless power transfer area and spatially offset from one another by a preselected spatial offset that minimizes inductive coupling between the first and second sets of cross-coupled segments, transmitting, from first and second radio frequency (RF) power sources electrically coupled to the first and second sets of cross-coupled segments, respectively, RF power across the pre-determined wireless power transfer area via near electromagnetic fields of the variable form factor transmitters such that a magnetic field associated with the near electromagnetic fields rotates in a pattern having a preselected shape.

Abstract: Wireless power receiver circuits and methods for use in wireless power transfer systems are provided for providing a constant current or voltage, depending on which is needed, to an electrical load. The wireless power receiver circuits are configured to shut down the resonant responses of the receiver circuits when electrical power is not needed by the load to reduce power consumption and avoid unnecessary heat dissipation. Additionally, a switching device of the wireless power receiver circuit that is used for shutting down the resonant response can operate at relatively low frequencies, and consequently, can be implemented using relatively low-speed, relatively inexpensive components.