Patent ID: 11888328
Assignee: WITRICITY CORPORATION
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 13:
14. A controller for controlling an active rectifier of a wireless power receiver that comprises a first transistor, a second transistor, a first snubber capacitor coupled in parallel to the first transistor, and a second snubber capacitor coupled in parallel to the second transistor, wherein the controller is coupled to the rectifier and is configured to perform the steps comprising:
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:
detecting phase information associated with the new value of the present input current, wherein detecting the phase information associated with the new value comprises:
detecting zero crossing information associated with the new value of the present input current; and
providing the zero crossing information to a phase-locked loop module, the module comprising (i) a XOR logic gate or (ii) a charge pump;

generating a PWM signal based on the detected phase information; and
driving at least one of the first and second transistors with the generated PWM signal, wherein the method further comprises:
setting a ramp signal associated with the second transistor to zero;
after detecting a first zero crossing information, discharging the first snubber capacitor thereby reducing an input voltage of the active rectifier to zero and turning on a body diode of the first transistor;
turning off the second transistor, thereby charging the second snubber capacitor to a load voltage of the wireless power receiver;
turning on the first transistor;
setting a ramp signal associated with the first transistor to zero;
after detecting a second zero crossing information, discharging the second snubber capacitor thereby reducing the input voltage of the active rectifier to zero and turning on a body diode of the second transistor;
turning off the first transistor, thereby charging the first snubber capacitor to the load voltage; and
turning on the second transistor.