Device and method for foreign object detection in wireless energy transfer

Apparatus for wireless power transfer, comprising a power transfer coil (111) configured for inductive power transfer and defining a first plane, a foreign object detecting device comprising at least one detection coil (31) defining a second plane substantially parallel to the first plane. The foreign object detecting device comprises a driver circuit coupled to the at least one detection coil for generating a magnetic field with the at least one detection coil and a control unit coupled to the driver circuit and configured to measure a value representative of a damping of the magnetic field. Each of the at least one detection coil is positioned relative to the power transfer coil such that a magnetic flux generated by the power transfer coil through a first portion (311) of the first area and through a second portion (312) of the first area, taking account of a polarity of the detection coil in the first portion and in the second portion, are of opposite sign and of substantial equal magnitude resulting in the detection coil having a magnetic coupling coefficient with respect to the power transfer coil of 0.2 or less.