Witricity Corporation

Massachusetts Institute of Technology

M.i.t.

Andre B Kurs

Morris P Kesler

Katherine L Hall

Aristeidis Karalis

Marin Soljacic

Andrew J Campanella

Konrad J Kulikowski

Eric R Giler

David A Schatz

Alexander Patrick McCauley

Arunanshu Mohan Roy

Noam Katz

Herbert Toby Lou

Ron Fiorello

Qiang Li

Peter H Fisher

Robert Moffatt

John Dimitris Joannopoulos

Volkan Efe

Milisav Danilovic

Steven J Ganem

Gozde Guckaya

Christopher Buenrostro

Matthew J MacDonald

Michael Sasha John

Maria Empar Rollano Hijarrubia

Matthew Dillon

Guillaume Lestoquoy

David R DeBaun

Hiroshi A Mendoza

Jude R Jonas

Nathan Andrew Pallo

Michael Alan Feldstein

Frank Pergal

Erika Ye

Hamik Amirkhani

Steve J Ganem

Jonathan Sirota

Damiano Patron

John D Joannopoulos

Frank J Pergal

Wireless power receivers include a first inductive element featuring a planar coil occupying a first plane and having first and second terminals, a first capacitive element connected to the first terminal, a second capacitive element connected to the first capacitive element at a third terminal and to the second terminal, a rectifier connected to the second terminal and third terminal such that an oscillating magnetic field will induce a current in the first inductive element, resulting in a voltage across the input of the rectifier, a communications modulation circuit, and a layer of magnetic material centered over the planar coil in a second plane parallel to the first plane.

Wireless power system modules

A wireless power transmitter includes a first inductive element featuring a planar coil occupying a first plane and having first and second terminals, a first capacitive element connected to the first terminal, an inverter configured to provide an oscillating voltage signal to the first inductive element, through the first capacitive element, such that the first inductive element generates an oscillating magnetic field for transmitting power in response to the oscillating voltage signal, and a layer of magnetic material, disposed over the planar coil in a second plane parallel to the first plane.

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.

PWM capacitor control

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.

Impedance adjustment in wireless power transmission systems and methods

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.

Wireless energy transfer

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.

Wireless power transfer systems for surfaces

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.

Wireless power transmission system enabling bidirectional energy flow

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.

Wireless power systems having interleaved rectifiers

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.

Foreign object detection in wireless energy transfer systems

Methods, systems, and devices for operating wireless power transfer systems. One aspect features a wireless energy transfer system that includes a transmitter, and a receiver. The transmitter has a transmitter-IMN and is configured to perform operations including performing a first comparison between a characteristic of a power of the transmitter and a target power. Adjusting, based on the first comparison, a reactance of the transmitter-IMN to adjust the power of the transmitter. The receiver has a receiver-IMN and is configured to perform operations including determining an efficiency of the wireless energy transfer system at a second time based on power data from the transmitter. Performing a second comparison between the efficiency at the second time and an efficiency of the wireless energy transfer system at a first time, the first time being prior to the second time. Adjusting, based on the second comparison, a reactance of the receiver-IMN.

Controlling wireless power transfer systems

Growing community of inventors

Chestnut Hill, MA, United States of America

Andre B Kurs