Patent ID: 8618778

Claim:
A coupling circuit for coupling a supply of electrical energy to an inductive load device, wherein the coupling circuit comprises a switching circuit, an energy transfer capacitance and a resonating capacitance; the resonating capacitance and the inductive load device together form a resonated load circuit having a natural resonant frequency; the switching circuit is configurable in a charging configuration by which the energy transfer capacitance is charged from the supply of electrical energy; the switching circuit is configurable in an injecting configuration by which the energy transfer capacitance is at least partly discharged into the resonated load circuit, thereby injecting a discrete pulse of energy into the resonated load circuit; the switching circuit is repetitively configurable in the charging configuration followed by the injecting configuration to transfer energy from the supply of electrical energy to the inductive load device, the energy transferred to the inductive load device circulating in the resonated load circuit at an oscillation frequency that is near or equal to the natural resonant frequency; and there is no injection of energy from the energy transfer capacitance into the resonated load circuit while energy for charging the energy transfer capacitance is being delivered from the supply to the switching circuit.