Wireless inductive power transfer

A power transmitter comprising:

• a communication inductor, wherein the communication inductor is configured to communicate with a power receiver;
• a detector,
• wherein the detector is configured to detect an impedance change of the communication inductor,
• wherein a presence of the power receiver is detected by the impedance change but no power transfer signal is generated when the power transmitter is in a standby mode,
• wherein the power transmitter is configured to provide a power transfer to the power receiver via a wireless inductive power transfer signal,
• wherein the wireless inductive power transfer signal is generated by the power transmitter when the power transmitter is in a power transfer mode;
• and
• a transmitter mode controller,
• wherein the transmitter mode controller is configured to initiate a transition from the standby mode to the power transfer mode in response to the detector detecting the impedance change,
• wherein the communication inductor is connected to a capacitor to form a resonance circuit, and
• wherein the detector is configured to apply an excitation signal causing oscillations to the resonance circuit,
• wherein the detector is configured to detect the impedance change from a measurement of at least one of a communication inductor voltage and a communication inductor current.