Counter wound inductive power supply
A contactless power supply is provided. The contactless power supply includes two or more primary coils for generating a region of cooperative magnetic flux generally therebetween. A portable device having a secondary coil can be positioned proximate this region of magnetic flux to receive wireless power from the contactless power supply. The spaced-apart primary coils can be wound in alternating directions about a common axis and driven in phase, or can be wound in a single direction about a common axis and driven approximately 180 degrees out of phase. The contactless power supply can include a plurality of primary coils in an adjustable array to accommodate multiple portable devices each with different secondary configurations and power consumption needs.
1. A contactless power supply comprising:
a power transfer surface to receive at least one remote device thereon, wherein the remote device includes an inductive secondary defining a centerline axis generally perpendicular to the power transfer surface;
a first primary coil array subjacent the power transfer surface and including a plurality of spaced-apart inductive primaries each being wound about an axis generally parallel to the power transfer surface such that the plurality of spaced-apart inductive primaries are co-axial; and
a power supply electrically connected to each of the plurality of inductive primaries, wherein the power supply is operable to selectively drive a first two of the plurality of inductive primaries to define a first region of cooperative electromagnetic flux between the first two of the plurality of inductive primaries and operable to selectively drive a second two of the plurality of inductive primaries to define a second region of cooperative electromagnetic flux between the second two of the plurality of inductive primaries.
2. The contactless power supply of claim 1 wherein:
the first two of the inductive primaries are wound in a common direction;
the power supply is operable to drive the first two of the plurality of inductive primaries substantially out of phase;
the second two of the inductive primaries are wound in a common direction; and
the power supply is operable to drive the second two of the plurality of inductive primaries substantially out of phase.
3. The contactless power supply of claim 1 wherein:
the first two of the plurality of inductive primaries are separated by a first distance; and
the second two of the plurality of inductive primaries are separated by a second distance different from the first distance.
4. The contactless power supply of claim 1 wherein the power supply is operable to monitor a characteristic of power in the plurality of inductive primaries to detect the presence of a remote device in proximity to the first primary coil array.
5. The contactless power supply of claim 1 further including a second primary coil array subjacent the power transfer surface including a plurality of spaced-apart inductive primaries each being wound about an axis generally orthogonal to the first primary coil array.
6. The contactless power supply of claim 1 wherein the power supply includes a driver and a switching circuit for simultaneously driving at least two of the plurality of inductive primaries substantially out of phase.
7. The contactless power supply of claim 1 wherein the power supply includes first and second drivers for simultaneously driving at least two of the plurality of inductive primaries substantially out of phase.
8. The contactless power supply of claim 1 wherein the first primary coil array includes a ferromagnetic core element.
9. The contactless power supply of claim 1 wherein the first primary coil array includes a substantially planar bobbin.
10. The contactless power supply of claim 1 wherein:
the first two of the inductive primaries are wound in opposite directions;
the power supply is operable to drive the first two of the plurality of inductive primaries substantially in phase;
the second two of the inductive primaries are wound in opposite directions; and
the power supply is operable to drive the second two of the plurality of inductive primaries substantially in phase.