Wireless power transfer

A power transmitter comprising:

• a receiver circuit, wherein the receiver circuit is configured to receive at least one message from a power receiver
• a transmitter coil,
• wherein the transmitter coils is configured to generate a power transfer signal,
• wherein the power transfer signal is generated in response to a drive signal;
• a driver circuit, wherein the driver circuit is configured to generate the drive signal;
• a power loop controller circuit,
• wherein the power loop controller circuit is configured to control the drive signal so as to adjust a power level of the power transfer signal,
• wherein the power control loop controller circuit is configured to apply changes to the power level of the power transfer signal in response to the at least one message;
• a mode memory circuit,
• wherein the mode memory circuit is configured to store at least one power level mode,
• wherein the at least one power level mode is associated with a reference power level;
• a mode circuit,
• wherein the mode circuit is configured to adapt the drive signal so as to set the power level of the power transfer signal to a first reference value in response to receiving a mode request message,
• wherein the first reference value corresponds to a first reference power level of a first power level mode,
• wherein the first power level mode is indicated in the mode request message,
• wherein the first power level mode is one of the at least one power level mode.