Sensor arrangement for a foreign object detection device

Abstract

The invention relates to a sensor arrangement () for a foreign object detection device which includes a current input () and a current output (), a multitude of detection cells (-), each comprising a sense coil and a capacitive element, forming a resonant tank. The sensor arrangement () further has a multitude of inputs leads (-) and a multitude of output leads (-), the total number of input and output leads being equal or smaller than the number of detection cells (-). Each detection cell is connected between one of the input leads (-) and one of the output leads (-), in a way that each of the detection cells (-) is connected to a different pair of input and output leads (--). An input selection circuit () allows to selectively establish an electrical connection between the current input () and one or more of the input leads (-) and an output selection circuit to () selectively establish an electrical connection between one or more of the output leads (-) and the current output (). According to the invention at least one detection cell (-) includes a decoupling element (D-D) connected in series to its resonant tank. The invention further relates to foreign object detection device for a wireless power transfer system, a primary part of a wireless power transfer system, a wireless power transfer system and a method for detecting a foreign object.