Witricity Corporation

Conor Joseph Rochford

Milisav Danilovic

Daniel Bronson

Morris P Kesler

Bryan Ashworth Esteban

Disclosed herein are methods and systems for controlling an active rectifier of a wireless power receiver. The exemplary methods can include determining a reference value of a current into the rectifier, the reference value being based on a load requirement; determining a required value change in a present input current into the rectifier based on the reference value; transmitting, to a wireless power transmitter, a signal representative of the required value change in the present input current; determining a new value of the present input current after transmitting the signal; and, when the new value is within a predetermined range of the required value change, driving at least one transistor in the rectifier with a PWM signal based on the new value.

Active rectification in wireless power systems

Exemplary protection circuitry for wireless power systems can include a battery disconnect circuit, a load dump protection circuit, and/or a coil disconnect circuit. One or more of these protection circuits may be employed by a wireless power receiver. Further, one or more of these protection circuits may enable a wireless power receiver to be able to protect itself independently from a wireless power transmitter, thereby increasing safety of the wireless power system.

Protection circuits for wireless power receivers

The disclosure features circuits and methods for protecting transistors of a wireless power receiver, which can be controlled by gate drivers powered by an auxiliary power source. The circuit can include a comparator configured to generate a signal indicating a comparison of a value of the auxiliary power source to a predetermined threshold, and a fault latch coupled to the comparator. The fault latch can be configured to trigger based on the generated signal and transmit a signal to respective inputs of the gate drivers to cause a latched-on state of respective gates of the transistors. Switches respectively coupled to the gate drivers can be configured to disconnect respective outputs of the gate drivers from the respective transistor gates. Gate hold-up circuits respectively coupled to the respective transistor gates can be configured to maintain the latched-on state of the respective transistor gates for a period of time.

Systems and methods for auxiliary power dropout protection

Disclosed herein are active rectifiers for wireless power receivers. The exemplary active rectifier can include a first diode coupled between a first input of the rectifier and an output of the rectifier; a first transistor coupled between the first input and ground; a first capacitive snubber coupled in parallel to at least one of: (i) the first diode or (ii) the first transistor. The example active rectifier can include a second diode coupled between a second input of the rectifier and the output; a second transistor coupled between the second input and ground; and a second capacitive snubber coupled in parallel to at least one of: (i) the second diode or (ii) the second transistor.

Disclosed herein are tunable reactance circuits configured to present a tunable or variable capacitive reactance when energized. The circuits can include a switch configured to be controlled by a gate driver, the gate driver configured to receive a control signal indicating an on-time of the switch; a diode coupled antiparallel to a switch; and one or more capacitors coupled in parallel to the diode. The tunable capacitive reactance can be based on the on-time of the switch and a total capacitance value of the one or more capacitors. The exemplary tunable reactance circuits may be used in wireless power transmitters and/or receivers for efficient power transmission and/or to deliver a particular level of power to a load.

Tunable reactance circuits for wireless power systems

Disclosed herein are systems and methods for determining a current of a resonator coil during operation of a wireless power system having the resonator coil, in which the resonator coil is coupled to a fixed capacitive network and a reactance circuit. The systems and methods can include determining a first signal which can include receiving a current in an inductor of the reactance circuit; converting the current to a voltage signal; and scaling the voltage signal. The systems and methods can include determining a second signal which can include receiving an output voltage at an output of the reactance circuit; dividing the output voltage; and integrating the divided scaled voltage to produce an inverted differentiated voltage signal. The methods can include summing the first signal and the second signal to produce a summed signal; and determining the current in the resonator coil based on the summed signal.

Systems and methods for determining coil current in wireless power systems

Methods and apparatus to control load power in a wireless power transfer system having one or more power receiving devices and one or more power transmitting sources. In embodiments, device temperature, current level, and/or other information can be used to control power to a load energized by a device.

Wireless power transmission system having power control

Methods and apparatus for a body diode conduction sensor configured for coupling to a switching element. In embodiments, the sensor comprises first and second voltage divider networks coupled to a voltage source and a diode coupled to the switching element and to the first voltage divider network, wherein the diode is conductive at times corresponding to body diode conduction of the switching element decreasing the DC average voltage at the output node of the first voltage divider network. A differential output voltage can be coupled to the first and second voltage divider networks with an output signal corresponding to a time of the body diode conduction of the switching element.

Diode conduction sensor

Methods and apparatus provide compensation for impedance changes in a network energized by an amplifier, such as a class E amplifier. In embodiments, bus voltage amplifier fundamental AC output voltage can be used to generate a feedback signal for adjusting impedance of one or more components in the network. In embodiments, the amplifier fundamental AC output voltage is determined from current to the load, wherein the load is coupled to the amplifier by an LCL impedance matching network.

Growing community of inventors

Boston, MA, United States of America

Conor Joseph Rochford