Wireless power transfer using parameters

A method of operating a power receiver comprising:

• receiving wireless power from a power transfer signal;
• synchronizing a time reference to a repeating time frame, wherein the repeating time frame comprises at least one power transfer interval and at least one detection interval;
• disconnecting a load during at least a portion of the at least one detection interval, wherein a timing of the disconnecting is dependent on the time reference;
• and
• switching between a first operational mode and a second operational mode for the at least one power transfer interval in response to a reliability measure of for the synchronization,
• wherein first power transfer parameters are used in the first operational mode and second power transfer parameters are used in the second operational mode.

A power receiver comprising:

• a synchronizer circuit,
• wherein the synchronizer circuit is arranged to perform a synchronization by synchronizing a time reference to a repeating time frame,
• wherein the repeating time frame comprises at least one power transfer interval and at least one detection interval;
• a load controller circuit,
• wherein a power transfer phase comprises at least two repeating time frames,
• wherein the load controller circuit is arranged to disconnect a load,
• wherein the load is disconnected during at least a portion of the at least one detection interval,
• wherein a timing of the disconnecting is dependent on the time reference;
• and
• a mode controller circuit,
• wherein the mode controller circuit is arranged to switch between a first operational mode and a second operational mode during a power transfer interval,
• wherein the switch is in response to a reliability measure of the synchronization,
• wherein first power transfer parameters are used in the first operational mode and the second power transfer parameters are used in the second operational mode,
• wherein the first power transfer parameters are different from the second power transfer parameters.