INDUCTIVE POWER TRANSFER
An inductive power transfer device for transmitting or receiving magnetic flux, the device comprising two co-planar and adjacent coils defining respective apertures and having a magnetically permeable core located to at least partially overlap both apertures; the two co-planar coils together defining a shape which is substantially equally extended in orthogonal directions.
1 . An inductive power transfer device for transmitting or receiving magnetic flux, the device comprising:
two co-planar and adjacent coils defining respective apertures and having a magnetically permeable core located to at least partially overlap both apertures;
the two co-planar coils together defining a shape which is substantially equally extended in orthogonal directions.
2 . The device of claim 1 , wherein an aspect ratio of the defined shape is between 0.8:1 and 1.2:1.
3 . The device of claim 1 , wherein the two co-planar coils are connected such that the apertures form poles of opposite polarity.
4 . The device of claim 1 , wherein the two co-planar coils are connected or driven such that a current flows in opposite directions in each of the two co-planar coils respectively.
5 . The device of claim 1 , further comprising a third coil having an aperture encompassing the respective apertures of the two co-planar coils.
6 . The device of claim 5 , wherein the third coil is arranged to conform to the shape defining the two co-planar coils.
7 . The device of claim 5 , wherein the third coil is driven at a 90 degree phase difference compared to the two co-planar coils.
8 . The device of claim 5 , further comprising:
a first compensation network coupled to the two co-planar coils;
a second compensation connected to the third coil;
wherein the first and second compensation networks each have a different power transfer characteristic.
9 . The device of claim 8 , wherein one of the compensation networks is a parallel tuned resonant circuit and the other compensation network is a series tuned resonant circuit.
10 . The device of claim 8 , wherein the first and second compensation networks share an AC ground and a high-side connection.
11 . The device of claim 1 , further comprising:
fourth and fifth co-planar and adjacent coils defining respective apertures and having a second magnetically permeable core located to at least partially overlap both apertures of the fourth and fifth coils;
the fourth and fifth co-planar coils together defining a second shape which is substantially equally extended in orthogonal directions;
the fourth and fifth coils overlapping the two co-planar coils and being rotated with respect to them.
12 . The device of claim 1 , further comprising:
fourth and fifth overlapping coils arranged in parallel planes and adjacent a second magnetically permeable core, wherein the overlap of the fourth and fifth coils is arranged to minimise mutual coupling between the fourth and fifth coils;
the fourth and fifth coils together defining a second shape which is substantially equally extended in orthogonal directions;
the fourth and fifth coils overlapping the two co-planar coils and being rotated with respect to them.
13 . The device of claim 1 , wherein a first of the two co-planar coils having an inner winding portion extending immediately along-side a corresponding inner winding portion of a second of the two co-planar coils, outer winding portions of the two co-planar coils defining the shape of the two co-planar coils, the shape being substantially orthogonally symmetric or having at least 4 lines of substantial symmetry in a first plane.
14 . The device of claim 13 wherein a density of the windings in the inner winding portion is more than the outer windings.
15 . The device of claim 13 wherein the core is a ferrite sheet extending to the outer windings.
16 . The device of claim 13 , wherein a current, in the inner winding portions, is in the same direction for the two co-planar coils.
17 . The device of claim 1 wherein the shape of the two co-planar coils is substantially square, circular, or diamond shaped.
18 . The device of claim 17 wherein each of the two co-planar coils are each substantially rectangular, semi circular, or triangle shaped.
19 . An inductive power transfer system comprising a transmitter and a receiver arranged to magnetically couple in order to transfer power between them:
the transmitter and the receiver each comprising:
two co-planar and adjacent coils defining respective apertures and having a magnetically permeable core located to at least partially overlap both apertures;
the two co-planar coils together defining a shape which is substantially equally extended in orthogonal directions;
a third coil having an aperture encompassing the respective apertures of the two co-planar coils;
a first compensation network coupled to the two co-planar coils;
a second compensation connected to the third coil;
wherein the first and second compensation networks each have a different power transfer characteristic;
the transmitter further comprising a single inverter driving both compensation networks, wherein the first and second compensation networks share an AC ground and a high-side connection;
the receiver further arranged wherein the first and second compensation networks are electrically decoupled and have respective rectifiers, an outputs of each respective rectifier being combined.
20 . An inductive power transmitter or receiver comprising a plurality of coil arrangements arranged into a coil array, each coil arrangement comprising:
two co-planar and adjacent coils defining respective apertures and having a magnetically permeable core located to at least partially overlap both apertures;
the two co-planar coils together defining a shape which is substantially equally extended in orthogonal directions;
wherein each coil arrangement is rotated 90 degrees with respect to an adjacent coil arrangement.