Foreign object detection apparatus and wireless charging system including the same
A foreign object detection apparatus including a plurality of object sensing devices positioned between a transmission pad and a reception pad of a wireless charging system; and a detection circuit configured to determine whether a foreign object is present between the transmission pad and the reception pad based on data received from the plurality of object sensing devices. Further, each of the plurality of object sensing devices includes a first coil unit wound with a first coil in a first direction, and a second coil unit wound with a second coil in a second direction different from the first direction; and the first coil unit and the second coil unit overlap each other.
1. A foreign object detection apparatus, comprising:
a plurality of object sensing devices positioned between a transmission pad and a reception pad of a wireless charging system; and
a detection circuit configured to determine whether a foreign object is present between the transmission pad and the reception pad based on data received from the plurality of object sensing devices,
wherein each of the plurality of object sensing devices includes
a first coil unit wound with a first coil in a first direction, and
a second coil unit wound with a second coil in a second direction different from the first direction,
wherein the first coil unit and the second coil unit overlap each other,
wherein an arrangement pattern of the plurality of object sensing devices is determined based on a shape of the transmission pad,
wherein each of the plurality of object sensing devices includes a first object sensing device and a second object sensing device alternately disposed with the first object sensing device, and
wherein the second object sensing device is disposed in a line with the first object sensing device, the first object sensing device is disposed such that the first coil unit is deposited on the second coil unit, and the second object sensing device is disposed such that the second coil unit is deposited on the first coil unit.
2. The foreign object detection apparatus of claim 1 , wherein the first coil includes a larger number of windings than the second coil.
3. The foreign object detection apparatus of claim 1 , wherein a first shape defined by windings of the first coil is smaller than a second shape defined by windings of the second coil.
4. The foreign object detection apparatus of claim 3 , wherein a number of windings of the first coil is determined based on a value obtained by multiplying a ratio between an area of the first shape and an area of the second shape by a number of windings of the second coil.
5. The foreign object detection apparatus of claim 3 , wherein the first shape and the second shape are polygons.
6. The foreign object detection apparatus of claim 3 , wherein the first shape is a first quadrangle and the second shape is a second quadrangle larger than the first quadrangle.
7. The foreign object detection apparatus of claim 6 , wherein a length of one side of the second quadrangle is twice a length of one side of the first quadrangle.
8. The foreign object detection apparatus of claim 3 , wherein the first shape is different from the second shape.
9. The foreign object detection apparatus of claim 3 , wherein the second coil unit is wound with the second coil in an outer region of the second shape, and is wound with the second coil to be separated from the first coil unit.
10. The foreign object detection apparatus of claim 9 , wherein the second coil unit is wound with the second coil one to three times.
11. The foreign object detection apparatus of claim 1 , wherein a number of windings of the first coil is determined by a location of the first coil unit on the transmission pad.
12. The foreign object detection apparatus of claim 11 , wherein the number of windings of the first coil is larger when the first coil unit is disposed on a transmission coil of the transmission pad than when the first coil unit is not disposed on the transmission coil of the transmission pad.
13. The foreign object detection apparatus of claim 1 , wherein the detection circuit determines whether the foreign object is present between the transmission pad and the reception pad based on a variation in impedance of the first coil unit.
14. The foreign object detection apparatus of claim 1 , wherein the detection circuit determines whether the foreign object is present between the transmission pad and the reception pad based on an induced voltage generated in the object sensing devices.
15. The foreign object detection apparatus of claim 1 ,
wherein the first object sensing device and the second object sensing device are deposited on each other.
16. The foreign object detection apparatus of claim 15 , wherein the detection circuit alternately operates the first object sensing device and the second object sensing device on a time division basis.
17. The foreign object detection apparatus of claim 3 , wherein the second shape defined by windings of the second coil in the second coil unit is at least one of a hexagon or a triangle.