Inductive power transfer apparatus
An inductive power transfer apparatus may be used for producing or receiving a magnetic field for inductive power transfer. The apparatus has a central coil and two end coils, one of the end coils being provided at each end of the central coil. Some turns of each of the end coils are on one side of the central coil and the remaining turns are on the other side. The end coils act to weaken or cancel flux on one side of the central coil and guide magnetic flux through the central coil to provide an arch shaped flux pattern beyond the apparatus on the other side of the central coil.
1. An inductive power transfer apparatus suitable for producing or receiving a magnetic field for inductive power transfer, the apparatus comprising:
a central coil having first and second ends and an axis therebetween; and
two end coils, one end coil being provided at or adjacent to each end of the central coil, each of the end coils being arranged to provide a first winding and a second winding,
wherein the first windings are provided on one side of the axis of the central coil, and the second windings are provided on the other side of the axis of the central coil, and
wherein the apparatus comprises a magnetically permeable structure which is located along the axis.
2. The apparatus as claimed in claim 1 wherein the end coils are each arranged at an angle relative to the central coil such that when energized the end coils guide magnetic flux through the central coil to provide an arch shaped flux pattern beyond the apparatus for inductive power transfer.
3. The apparatus as claimed in claim 1 wherein the end coils are arranged relative to the central coil such that when energized with a power source magnetic fields produced by each coil augment each other on a first side of the apparatus and substantially weaken each other on a second side of the apparatus opposite to the first side.
4. The apparatus as claimed in claim 1 wherein the first windings are provided on one side of the permeable structure and the second windings are provided on another side of the permeable structure.
5. The apparatus as claimed in claim 1 comprising a further coil adapted to produce or receive a magnetic flux component in a direction substantially orthogonal to the direction of a magnetic flux component produced or received by the central coil.
6. The apparatus as claimed in claim 1 wherein the first and second windings comprise flat windings.
7. An inductive power transfer apparatus suitable for producing or receiving a magnetic field for inductive power transfer, the apparatus comprising:
a central coil having first and second ends and an axis therebetween;
two end coils, each of the end coils being arranged to provide a first winding and a second winding, the first and second windings comprising flat windings;
one end coil being provided at or adjacent to each end of the central coil, and one or more turns of each of the end coils being on one side of the axis of the central coil and the remaining turns being on the other side of the axis; and
the end coils being arranged at an angle relative to the central coil and operable when energized to weaken or cancel flux on one side of the axis and guide magnetic flux through the central coil to provide an arch shaped flux pattern beyond the apparatus on the other side of the axis for inductive power transfer,
wherein the apparatus comprises a magnetically permeable structure which is located along the axis.
8. The apparatus as claimed in claim 7 wherein a further coil is provided at a side of the apparatus where flux is produced in use, a center axis of a winding of the further coil being arranged in a direction orthogonal to the axis of the central coil.
9. The apparatus as claimed in claim 7 wherein the one or more turns of each end coil are provided on one side of the permeable structure and the remaining turns are provided on another side of the permeable structure.