Abstract: Wireless energy transfer apparatus include, in at least one aspect, a device resonator configured to supply power for a load by receiving wirelessly transferred power from a source resonator; a temperature sensor positioned to measure a temperature of a component of the apparatus; a tunable component coupled to the device resonator to adjust a resonant frequency of the device resonator, an effective impedance the device resonator, or both; and control circuitry configured to, in response to detecting a temperature condition using the temperature sensor, (i) tune the tunable component to adjust the resonant frequency of the device resonator, the effective impedance of the device resonator, or both, and (ii) signal the source resonator regarding the temperature condition to cause an adjustment of a resonant frequency of the source resonator, a power output of the source resonator, or both.

Abstract: Methods, systems, and devices for controlling a variable capacitor. One aspect features a variable capacitance device that includes a capacitor, a first transistor, a second transistor, and control circuitry. The control circuitry is configured to adjust an effective capacitance of the capacitor by performing operations including detecting a zero-crossing of an input current at a first time. Switching off the first transistor. Estimating a first delay period for switching the first transistor on when a voltage across the capacitor is zero. Switching on the first transistor after the first delay period from the first time. Detecting a zero-crossing of the input current at a second time. Switching off the second transistor. Estimating a second delay period for switching the second transistor on when a voltage across the capacitor is zero. Switching on the second transistor after the second delay period from the second time.

Abstract: The disclosure features wireless energy transfer sources that include at least two source resonators and a power source, where: each of the at least two source resonators has a nominal impedance when a device resonator is not positioned on or near any of the at least two source resonators, the nominal impedances of each of the at least two source resonators varying by 10% or less from one another; and the at least two source resonators are configured so that during operation of the wireless energy transfer source, when a device resonator is positioned on or near a first one of the at least two source resonators: (a) the impedance of the first source resonator is reduced to a value smaller than the nominal impedances of each of the other resonators by a factor of 2 or more.

Abstract: The disclosure features wireless energy transfer sources that include at least two source resonators and a power source, where: each of the at least two source resonators has a nominal impedance when a device resonator is not positioned on or near any of the at least two source resonators, the nominal impedances of each of the at least two source resonators varying by 10% or less from one another; and the at least two source resonators are configured so that during operation of the wireless energy transfer source, when a device resonator is positioned on or near a first one of the at least two source resonators: (a) the impedance of the first source resonator is reduced to a value smaller than the nominal impedances of each of the other resonators by a factor of 2 or more.

Abstract: In a first aspect, the disclosure features apparatuses for wireless power transfer, the apparatuses including a plurality of magnetic elements joined together to form a magnetic component extending in a plane, where discontinuities in the magnetic component between adjacent magnetic elements define gaps in the magnetic component, a coil including one or more loops of conductive material positioned, at least in part, on a first side of the plane. The apparatuses include a conductive shield positioned on a second side of the plane and which includes one or more openings positioned relative to the gaps.

Abstract: Described herein are improved configurations for a wireless power transfer. Described are methods and designs to reduce and manage heating and heat dissipation in resonator structures. Configuration and orientation of magnetic material as well as heat sinking material with respect to the dipole moment of the resonator is used to reduce and control thermal properties of the resonator structure and reduce the effects of heating on the performance of wireless power transfer.

Abstract: A device for testing a wireless power network, where the network includes at least one power source, at least one load, and resonators configured to couple wireless power from the at least one power source to the at least one load. The device includes: a user interface for receiving input from a user and providing information to the user; a measurement module for measuring (directly or indirectly) at least one operational characteristic of the wireless power network and information about the geometric arrangement of the multiple resonators in the wireless power network; a memory for storing design specifications about the wireless power network; and an electronic processor configured to calculate information about a performance of the wireless power network based on the operational characteristic, the information about the geometric arrangement of the resonators, and the stored design specifications, and further configured to provide the performance information through the user interface.

Abstract: The disclosure features wireless energy transfer sources that include at least two source resonators and a power source, where: each of the at least two source resonators has a nominal impedance when a device resonator is not positioned on or near any of the at least two source resonators, the nominal impedances of each of the at least two source resonators varying by 10% or less from one another; and the at least two source resonators are configured so that during operation of the wireless energy transfer source, when a device resonator is positioned on or near a first one of the at least two source resonators: (a) the impedance of the first source resonator is reduced to a value smaller than the nominal impedances of each of the other resonators by a factor of 2 or more.

Abstract: The disclosure features wireless power transfer systems that include a power transmitting apparatus configured to wirelessly transmit power, a power receiving apparatus connected to an electrical load and configured to receive power from the power transmitting apparatus, and a controller connected to the power transmitting apparatus and configured to receive information about a phase difference between output voltage and current waveforms in a power source of the power transmitting apparatus, and to adjust a frequency of the transmitted power based on the measured phase difference.

Abstract: In a first aspect, the disclosure features apparatuses for wireless power transfer, the apparatuses including a coil formed of a conductive material. The coil includes a plurality of loops, where the plurality of loops defines an internal region of the coil that extends along a coil axis. The apparatuses include a magnetic component, where the magnetic component is disposed in the internal region and extends in a first direction parallel to the coil axis and in a second direction perpendicular to the coil axis. A maximum dimension of the magnetic component measured in the second direction varies along the first direction.

Abstract: A wireless power receiver is coupled to an impedance matching network, the impedance matching network having a first node and a second node. Coupled to the first node is a first branch having a first positive reactance and a second branch having a first negative reactance, wherein an absolute value of the first positive reactance is different from an absolute value of the first negative reactance, and coupled to the second node is a third branch having a second positive reactance and a fourth branch having a second negative reactance, wherein an absolute value of the second positive reactance is different from an absolute value of the second negative reactance.

Abstract: In a first aspect, the disclosure features apparatuses for wireless power transfer, the apparatuses including a plurality of magnetic elements joined together to form a magnetic component extending in a plane, where discontinuities in the magnetic component between adjacent magnetic elements define gaps in the magnetic component, a coil including one or more loops of conductive material positioned, at least in part, on a first side of the plane. The apparatuses include a conductive shield positioned on a second side of the plane and which includes one or more openings positioned relative to the gaps.

Abstract: The disclosure features wireless power transfer systems that include a power transmitting apparatus configured to wirelessly transmit power, a power receiving apparatus connected to an electrical load and configured to receive power from the power transmitting apparatus, and a controller connected to the power transmitting apparatus and configured to receive information about a phase difference between output voltage and current waveforms in a power source of the power transmitting apparatus, and to adjust a frequency of the transmitted power based on the measured phase difference.

Abstract: In a first aspect, the disclosure features apparatuses for wireless power transfer, the apparatuses including a coil formed of a conductive material. The coil includes a plurality of loops, where the plurality of loops defines an internal region of the coil that extends along a coil axis. The apparatuses include a magnetic component, where the magnetic component is disposed in the internal region and extends in a first direction parallel to the coil axis and in a second direction perpendicular to the coil axis. A maximum dimension of the magnetic component measured in the second direction varies along the first direction.

Abstract: A wireless power system for powering a television includes a source resonator, configured to generate an oscillating magnetic field, and at least one television component attached to at least one device resonator, wherein the at least one device resonator is configured to wirelessly receive power from the source resonator via the oscillating magnetic field when the distance between the source resonator and the at least one device resonator is more than 5 cm, and wherein at least one television component draws at least 10 Watts of power.

Abstract: A device for testing a wireless power network is disclosed. The network includes at least one power source, at least one load, and multiple resonators configured to couple wireless power from the at least one power source to the at least one load.

Abstract: The disclosure features systems for wireless power transfer that include a resonator featuring a coil with at least two windings and at least one inductor having an inductance value, where the at least one inductor is connected in series to at least one of the windings, and where the inductance value is selected so that when the coil carries a current during operation of the system, the at least one inductor maintains a distribution of current flows among the at least two windings such that for each of the at least two windings, an actual current flow in the winding differs from a target current flow for the winding by 10% or less.

Abstract: A wireless power system for powering a television includes a source resonator, configured to generate an oscillating magnetic field, and at least one television component attached to at least one device resonator, wherein the at least one device resonator is configured to wirelessly receive power from the source resonator via the oscillating magnetic field when the distance between the source resonator and the at least one device resonator is more than 5 cm, and wherein at least one television component draws at least 10 Watts of power.

Abstract: A wireless power system for powering a television includes a source resonator, configured to generate an oscillating magnetic field, and at least one television component attached to at least one device resonator, wherein the at least one device resonator is configured to wirelessly receive power from the source resonator via the oscillating magnetic field when the distance between the source resonator and the at least one device resonator is more than 5 cm, and wherein at least one television component draws at least 10 Watts of power.

Abstract: A wireless power system for powering a device having an electronic display includes: a device resonator including a loop of conductive material, the device resonator being coupled with an electronic display component; a matching network coupled with the loop of conductive material and including capacitive elements; and power and control circuitry coupled with the matching network at two terminals and configured to connect with a load of the electronic display component; wherein the matching network is configured to provide voltages of equal magnitude and opposite sign at the terminals when coupling power from the device resonator to the power and control circuitry; and wherein the device resonator is configured to wirelessly receive power from a source resonator via an oscillating magnetic field generated by the source resonator.