Power transmitter and method for wirelessly transferring power

A method of operation for a wireless power transfer system including a power receiver for receiving a power transfer from a power transmitter via a wireless inductive power transfer signal;

• the power transmitter including:
• a parallel resonance circuit comprising at least a capacitive impedance and an inductive impedance, the inductive impedance comprising a transmitter coil for generating the power transfer signal;
• a power source having a current sink terminal and at least one power source terminal for providing current to the parallel resonance circuit, the power source being arranged to limit a rate of change of a current drawn from the power source terminal;
• a first switch element having a first terminal coupled to a first end of the parallel resonance circuit and a second terminal coupled to the current sink terminal;
• a second switch element having a first terminal coupled to a second end of the parallel resonance circuit and a second terminal coupled to the current sink terminal;
• a driver for generating at least one cyclic drive signal for the first switch element and the second switch element;
• the method comprising:
• the driver generating the at least one cyclic drive signal such that each cycle comprises a first time interval in which the first switch element is closed and the second switch element is open, a second time interval in which the first switch element is open and the second switch element is closed;
• and a third time interval in which both the first switch element and the second switch element are closed, the third time interval being between the first time interval and the second time interval.