Foreign object detection in wireless energy transfer systems

A method, comprising:

• activating a power source to generate a magnetic field between the power source and a power receiver of a wireless power transfer system;
• measuring an electrical signal generated by a detector positioned between the power source and the power receiver;
• and
• determining whether debris is positioned between the power source and the power receiver by comparing baseline information to the measured electrical signal,
• wherein the baseline information comprises information about an electrical signal generated by the detector when no debris is positioned between the power source and the power receiver;
• and
• wherein comparing the baseline information to the measured signal comprises determining mean and covariance matrices for the baseline information and determining whether debris is positioned between the power source and the power receiver based on the mean and covariance matrices.

An apparatus for detecting debris, the apparatus comprising:

• a detector, wherein the detector is configured so that when the detector is positioned between a power source and a power receiver of a wireless power transfer system, the detector generates an electrical signal based on a magnetic field between the power source and the power receiver;
• and
• control electronics coupled to the detector, wherein the control electronics are configured to:
• measure the electrical signal of the detector in response to a magnetic field between the power source and the power receiver;
• and
• determine whether debris is positioned between the power source and the power receiver by comparing baseline information to the measured electrical signal,
• wherein the baseline information comprises information about an electrical signal generated by the detector when no debris is positioned between the power source and the power receiver;
• and
• wherein the control electronics are configured to compare the baseline information to the measured signal by determining mean and covariance matrices for the baseline information and determining whether debris is positioned between the power source and the power receiver based on the mean and covariance matrices.