Inverter for inductive power transfer

Abstract

An inverter for inductive power transfer is disclosed. The inverter comprises a first inductor and a switching element in series between power supply terminals, the switching element being operable to be switched at a first frequency; a first capacitance in parallel with the switching element between the first inductor and a power supply terminal; a first tank circuit in parallel with the first capacitance, the first tank circuit comprising a second inductor and a second capacitance, wherein the second capacitance is arranged in series with the second inductor; a second tank circuit in parallel with the first capacitance; and a third capacitance in series with the first inductor between the first tank circuit and the second tank circuit, wherein the second tank circuit comprises a transmitter coil and a fourth capacitance, the fourth capacitance being arranged in parallel or series with the transmitter coil; wherein the fourth capacitance is selected such that the resonant frequency of the second tank circuit is not equal to the first frequency, and wherein the second inductor and the second capacitance are selected such that the resonant frequency of the first tank circuit is an integer multiple, greater than one, of the first frequency.