Inductive power transfer transmitter and system

An inductive power transfer transmitter according to any previous claim wherein there is reduced current output from the inverter sub-circuit as a result of the two tuning networks that decouple the inverter from the transmitter coil.

An inductive power transfer transmitter according to any previous claim wherein there is reduced power loss in the inverter sub-circuit.

An inductive power transfer transmitter according to any previous claim wherein the tuned circuit further comprises at least one further additional component to improve power factor of power supplied from the inverter sub-circuit to the transmitting coil.

An inductive power transfer transmitter according to any previous claim wherein the at least one further additional component is a variable component to vary the power factor.

An inductive power transfer transmitter according to any previous claim wherein the inductor and/or capacitor and/or the first additional component are arranged in the tuned circuit to provide filtering.

An inductive power transfer transmitter according to any previous claim wherein the tuned circuit comprises a variable component that is a variable to vary the portion of current through transmitting coil.

An inductive power transfer transmitter according to any previous claim, wherein the transmitting coil, the inductor, the capacitor, and the first additional component are each placed on a separate branch of the tuned circuit.

An inductive power transfer transmitter according to any previous claim wherein the capacitor, the first additional component and the transmitting coil are connected in parallel.

An inductive power transfer transmitter according to any previous claim, wherein the plurality of components are arranged on the tuned circuit such that the tuned circuit can be remodelled as if the transmitting coil is series tuned so that the tuned circuit can vary current through the transmitting coil to compensate for variations in K coefficient.

An inductive power transfer transmitter according to any previous claim, wherein the first and second tuning networks together are Norton and Thevenin equivalent of a series tuned circuit to vary current through a transmitting coil to compensate for variations in K coefficient, while comprising one or more components, optionally parallel to the transmitting coil, to decouple the inverter from the transmitter coil.

An inductive power transfer transmitter according to any previous claim, wherein the tuned circuit can be remodelled by:

• applying Norton's theorem to transform a series connection of a voltage source (provided by the voltage of the inverter sub-circuit), the inductor and the capacitor into a parallel connection of a current source, the inductor and the capacitor, for creating an appearance of the first tuning network providing a current source for the transmitting coil, and
• applying Thevenin's theorem to transform a parallel connection of the current source, the first additional component, and the transmitting coil into a series connection of a voltage source, the first additional component and the transmitting coil, such that the transmitting coil appears series tuned.

An inductive power transfer transmitter according to any previous claim, wherein the tuned circuit further comprises a third additional component.

An inductive power transfer transmitter according to any previous claim, wherein the first additional component is a a capacitor, and/or an inductor and/or a combination of one or more capacitors and one or more inductors.

An inductive power transfer transmitter according to any previous claim, wherein the second additional component is an inductor and/or a capacitor and/or a combination of one or more capacitors and one or more inductors.

An inductive power transfer transmitter according to any previous claim, wherein the third additional component is an inductor and/or a capacitor and/or a combination of one or more capacitors and one or more inductors.