Abstract: Certain aspects of the present disclosure provide methods and apparatus for multi-phase coil control in power transfer systems. One example power transfer device generally includes a plurality of coils configured to generate at least one charging field, the plurality of coils comprising a first coil and a second coil, and a controller configured to identify that a coupling factor between the first coil and a third coil, which is external to the power transfer device, is at or below a threshold, and to adjust, based on the identification, one or more parameters associated with a current applied to the first coil to transfer power from the first coil to the second coil.

Abstract: In certain aspects, methods and systems for controlling power transfer at a wireless power receiver are disclosed. In certain aspects, a method includes determining a duty cycle of a DC-DC converter of the wireless power receiver. The method further includes determining a duty cycle limit for an AC switching controller based on the determined duty cycle. The method further includes determining an operational duty cycle for the AC switching controller. The method further includes comparing the operational duty cycle to the duty cycle limit. The method further includes adjusting at least one of a desired voltage and current input to the DC-DC converter when the operational duty cycle is greater than the duty cycle limit.

Abstract: Certain aspects of the present disclosure provide methods and apparatus for multi-phase coil control in power transfer systems. One example power transfer device generally includes a plurality of coils configured to generate at least one charging field, the plurality of coils comprising a first coil and a second coil, and a controller configured to identify that a coupling factor between the first coil and a third coil, which is external to the power transfer device, is at or below a threshold, and to adjust, based on the identification, one or more parameters associated with a current applied to the first coil to transfer power from the first coil to the second coil.

Abstract: 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.

Abstract: In certain aspects, methods and systems for controlling power transfer at a wireless power receiver are disclosed. In certain aspects, a method includes determining a duty cycle of a DC-DC converter of the wireless power receiver. The method further includes determining a duty cycle limit for an AC switching controller based on the determined duty cycle. The method further includes determining an operational duty cycle for the AC switching controller. The method further includes comparing the operational duty cycle to the duty cycle limit. The method further includes adjusting at least one of a desired voltage and current input to the DC-DC converter when the operational duty cycle is greater than the duty cycle limit.

Abstract: An apparatus for transmitting charging power wirelessly to a vehicle is provided. The apparatus comprises a first coupler having a first reactance at an operating frequency and configured to wirelessly receive power from a power source, the first coupler wound on a ferromagnetic core. The apparatus comprises a first capacitor having a second reactance at the operating frequency and electrically connected in series with the first coupler, the second reactance having a magnitude equal to a magnitude of the first reactance. The apparatus comprises a second capacitor electrically connected in parallel across the first coupler and the first capacitor. The apparatus comprises a first base coupler configured to be electrically connected in parallel across the second capacitor via a first switch. A magnitude of a peak voltage across the second capacitor is proportional to a magnitude of a peak voltage induced in the first coupler at the operating frequency.

Abstract: In certain aspects, methods and systems for controlling power transfer at a wireless power receiver are disclosed. In certain aspects, a method includes determining a duty cycle of a DC-DC converter of the wireless power receiver. The method further includes determining a duty cycle limit for an AC switching controller based on the determined duty cycle. The method further includes determining an operational duty cycle for the AC switching controller. The method further includes comparing the operational duty cycle to the duty cycle limit. The method further includes adjusting at least one of a desired voltage and current input to the DC-DC converter when the operational duty cycle is greater than the duty cycle limit.

Abstract: 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.

Abstract: Certain aspects of the present disclosure are generally directed to apparatus and techniques for apparatus for wireless charging. The apparatus generally includes a first wireless charging element, and transmit circuitry coupled to the first wireless charging element and configured to supply power to the first wireless charging element to transmit a wireless charging field to a vehicle. In certain aspects, the apparatus also includes a controller coupled to the transmit circuitry and configured to determine a charging condition indicative of a speed of the vehicle, and adjust the power supplied to the first wireless charging element via the transmit circuitry based on the determination.

Abstract: A method of operating a wireless-power receiver comprises: determining a first resonant frequency of a resonant circuit, of the wireless-power receiver, corresponding to a first time at which the wireless-power receiver is disposed at a first longitudinal offset from a power transmitter, the first longitudinal offset being relative to a length of a device containing the wireless-power receiver; determining a second resonant frequency of the resonant circuit, corresponding to a second time at which the wireless-power receiver is disposed at a second longitudinal offset from the power transmitter, the second longitudinal offset being relative to the length of the device containing the wireless-power receiver, and the first longitudinal offset being different from the second longitudinal offset; and determining a lateral misalignment of the wireless-power receiver relative to a wireless-power transmitter based on the first resonant frequency and the second resonant frequency.

Abstract: According to some implementations, an apparatus for transmitting charging power wirelessly to a load is provided. The apparatus comprises at least one ferrite structure comprising a first ferrite portion, a second ferrite portion comprising at least a first ferrite leg, a second ferrite leg, and a third ferrite leg, each physically separated from the first ferrite portion by a first distance, and a third ferrite portion positioned between the second ferrite leg and the first ferrite portion and physically contacting the second ferrite leg. The at least one ferrite structure further comprises a coil wound around the second ferrite leg and configured to generate an alternating current under influence of an alternating magnetic field.

Abstract: Certain aspects of the present disclosure are generally directed to apparatus and techniques for wirelessly charging a device. An exemplary method generally includes receiving, at a first wireless power transfer device, a synchronization signal indicative of a phase for generating a wireless charging field, determining an adjusted phase for generating the wireless charging field based, at least in part, on the received synchronization signal and one or more measurements taken at least one of the first wireless power transfer device or a second wireless power transfer device, wherein the one or more measurements are indicative of a phase difference between the first wireless power transfer device and the second wireless power transfer device, and generating, at the first wireless power transfer device, the wireless charging field with the adjusted phase.

Abstract: This disclosure provides systems, methods and apparatus including a magnetic flux device configured to transmit or receive magnetic flux to or from a space beyond the magnetic flux device. In certain configurations, the magnetic flux device can include a first coil with a first layer and second layer, a second coil with a third layer and fourth layer, and a magnetically permeable material with the first coil extending over a first edge of the magnetically permeable material and the second coil extending over a second edge of the magnetically permeable material. In certain other configurations, the magnetic flux device can include a first conductive structure including a first coil and a second coil enclosing a first area and a second area, respectively. The magnetic flux device can further include a second conductive structure with at least a first planar portion of the first conductive structure being substantially coplanar with a second planar portion of the second conductive structure.

Abstract: A method of determining a value of a magnetic characteristic of a wireless-power receiver system includes: obtaining a first frequency indication of a first resonant frequency of a power reception circuit of the wireless-power receiver system corresponding to a power transmit circuit and the power reception circuit being in a first state having a first combined circuit configuration; obtaining a second frequency indication of a second resonant frequency of the power reception circuit corresponding to the combination of the power transmit circuit and the power reception circuit being in a second state having a second combined circuit configuration, the first combined circuit configuration differing from the second combined circuit configuration by at least one of component content or a value of at least one component; and using the first frequency indication and the second frequency indication to determine the value of the magnetic characteristic of the wireless-power receiver system.

Abstract: The present disclosure describes aspects of a vehicle-based beacon mode for wireless electric vehicle charging. In some aspects, a circuit for receiving wirelessly transferred power includes a coil connected to boost circuitry configured to convert received power to a form suitable for storage. The circuit also includes beacon circuitry connected to a voltage source that, in combination with portions of the boost circuitry, enables current to be driven into the coil to generate a beacon signal. Based on this beacon signal, a base charging unit can detect the presence of the circuit and initiate the wireless transmission of power to the circuit without additional out-of-band communication. Further, the beacon circuitry may be compatible with, or protected from, current of the received power such that the circuit can seamlessly transition from generating the beacon signal to converting the received power without active reconfiguration, synchronization, or state control.

Abstract: A method of operating a wireless-power receiver comprises: determining a first resonant frequency of a resonant circuit, of the wireless-power receiver, corresponding to a first time at which the wireless-power receiver is disposed at a first longitudinal offset from a power transmitter, the first longitudinal offset being relative to a length of a device containing the wireless-power receiver; determining a second resonant frequency of the resonant circuit, corresponding to a second time at which the wireless-power receiver is disposed at a second longitudinal offset from the power transmitter, the second longitudinal offset being relative to the length of the device containing the wireless-power receiver, and the first longitudinal offset being different from the second longitudinal offset; and determining a lateral misalignment of the wireless-power receiver relative to a wireless-power transmitter based on the first resonant frequency and the second resonant frequency.

Abstract: A method of determining a value of a magnetic characteristic of a wireless-power receiver system includes: obtaining a first frequency indication of a first resonant frequency of a power reception circuit of the wireless-power receiver system corresponding to a power transmit circuit and the power reception circuit being in a first state having a first combined circuit configuration; obtaining a second frequency indication of a second resonant frequency of the power reception circuit corresponding to the combination of the power transmit circuit and the power reception circuit being in a second state having a second combined circuit configuration, the first combined circuit configuration differing from the second combined circuit configuration by at least one of component content or a value of at least one component; and using the first frequency indication and the second frequency indication to determine the value of the magnetic characteristic of the wireless-power receiver system.

Abstract: In certain aspects, methods and systems for controlling power transfer at a wireless power receiver are disclosed. In certain aspects, a method includes determining a duty cycle of a DC-DC converter of the wireless power receiver. The method further includes determining a duty cycle limit for an AC switching controller based on the determined duty cycle. The method further includes determining an operational duty cycle for the AC switching controller. The method further includes comparing the operational duty cycle to the duty cycle limit. The method further includes adjusting at least one of a desired voltage and current input to the DC-DC converter when the operational duty cycle is greater than the duty cycle limit.

Abstract: Certain aspects of the present disclosure are generally directed to apparatus and techniques for wirelessly charging a device. An exemplary method generally includes receiving, at a first wireless power transfer device, a synchronization signal indicative of a phase for generating a wireless charging field, determining an adjusted phase for generating the wireless charging field based, at least in part, on the received synchronization signal and one or more measurements taken at least one of the first wireless power transfer device or a second wireless power transfer device, wherein the one or more measurements are indicative of a phase difference between the first wireless power transfer device and the second wireless power transfer device, and generating, at the first wireless power transfer device, the wireless charging field with the adjusted phase.

Abstract: Certain aspects of the present disclosure are generally directed to apparatus and techniques for apparatus for wireless charging. The apparatus generally includes a first wireless charging element, and transmit circuitry coupled to the first wireless charging element and configured to supply power to the first wireless charging element to transmit a wireless charging field to a vehicle. In certain aspects, the apparatus also includes a controller coupled to the transmit circuitry and configured to determine a charging condition indicative of a speed of the vehicle, and adjust the power supplied to the first wireless charging element via the transmit circuitry based on the determination.