WIRELESS POWER TRANSMITTER AND METHOD OF OPERATION THEREFOR

A power transmitter () comprises a driver () generating a drive signal for a transmitter coil to generate a power transfer signal during a power transfer time interval and an electromagnetic test signal during a measurement time interval. A set of balanced detection coils () comprise two detection coils arranged such that signals induced in the two detection coils by an electromagnetic field generated by the transmitter coil compensate each other. An estimation circuit () determines a position/coupling factor estimate for the power receiver () in response to signals from the plurality of sets of balanced detection coils () during the at least one measurement time interval.