US Patent 10181759 Dynamic mutual sensing foreign object detection loops

Techniques for detecting a presence of a foreign object within a region for wirelessly transferring power to charge an electric vehicle are discloses. An example apparatus according to the disclosure includes a foreign object detection (FOD) structure including a transmitting loop structure, a receiving loop structure galvanically isolated from the transmitting loop structure and positioned relative to the transmitting loop structure such that a magnetic field generated by the transmitting loop structure induces a first voltage in the receiving loop structure, wherein the first voltage is below a threshold value, and a control circuit configured to drive the transmitting loop structure and detect a change in a magnitude of the first voltage in the receiving loop structure in response to the presence of the foreign object within the magnetic field.