Wireless inductive power transfer

A method of operating a power transmitter of an inductive power transfer system, wherein the power transfer system comprises the power transmitter and a power receiver, wherein the inductive power transfer system supports communication from the power receiver to the power transmitter based on load modulation, the method comprising:

• generating a wireless power signal for the power receiver when in a power transfer phase;
• receiving a first message comprising a standby power signal requirement for the power signal during a standby phase;
• and
• providing the power signal in accordance with the standby power signal requirement during the standby phase,
• wherein the first message indicates a maximum duration of an interval in the standby phase,
• wherein no power signal is provided by the power transmitter during the standby phase.

A method of operating a power receiver of an inductive power transfer system, wherein the power transfer system comprises a power transmitter for generating a wireless power signal for the power receiver when in a power transfer phase, wherein the inductive power transfer system supports communication from the power receiver to the power transmitter based on load modulation of the wireless power signal, the method comprising:

• extracting power from the wireless power signal when in the power transfer phase;
• transmitting a first message to the power transmitter, wherein the first message comprises a standby power signal requirement for the power signal during a standby phase;
• and
• receiving the power signal when in the standby phase,
• wherein the first message indicates a maximum duration of an interval in the standby phase,
• wherein no power signal is provided by the power transmitter during the standby phase.

A power receiver circuit for an inductive power transfer system, comprising:

• a power circuit, wherein the power circuit is arranged to extract power from a wireless power signal when in a power transfer phase;
• a transmitter circuit,
• wherein the transmitter circuit is arranged to transmit a first message to a power transmitter,
• wherein the first message comprises a standby power signal requirement for the wireless power signal during a standby phase;
• and
• a receiver circuit, wherein the receiver circuit is arranged to receive the power signal when in the standby phase,
• wherein the inductive power transfer system comprises a power transmitter circuit,
• wherein the power transmitter circuit is arranged to generate a wireless power signal when in a power transfer phase,
• wherein the inductive power transfer system supports communication from the power receiver circuit to the power transmitter circuit based on a load modulation of the wireless power signal,
• wherein the first message indicates a maximum duration of an interval in the standby phase,
• wherein no power signal is provided by the power transmitter circuit during the standby phase.