Patent ID: 8143746

Claim:
A device for a wireless power transfer system, the system having a wireless power transmitter (TX) and a wireless power receiver (RX), wherein: the wireless power transmitter comprises: a TX resonant circuit that resonates at a TX resonant frequency; and a signal generator that applies a generator signal having a generator frequency to the TX resonant circuit; the wireless power receiver comprises an RX resonant circuit that resonates at an RX resonant frequency; at least one of the wireless power transmitter and the wireless power receiver comprises a power detector that measures power in the corresponding resonant circuit; at least one of the wireless power transmitter and the wireless power receiver comprises an auto-tuner that generates at least one tuning parameter based on the measured power, wherein the auto-tuner comprises: a perturbation signal generator that generates a perturbation signal; a phase-sensitive detector that receives a cost-function signal generated by the power detector based on the measured power and the perturbation signal and generates a filtered signal; a negative-feedback controller that modifies the filtered signal to generate a modified signal; and a summation node that combines the perturbation signal and the modified signal to generate the at least one tuning parameter; the at least one tuning parameter is used to adjust at least one of the generator frequency, the TX resonant frequency, and the RX resonant frequency; the device is one of the wireless power transmitter and the wireless power receiver; and the device comprises at least one of the power detector and the auto-tuner.