Systems and Methods for Detecting Wireless Power Receivers and Other Objects at a Near-Field Charging Pad

A non-transitory computer-readable storage medium storing executable instructions that, when executed by a near-field charging pad with a plurality of power-transfer zones that each respectively include at least one power-transferring element and a signature-signal receiving circuit, and one or more processors, cause the near-field charging pad to:

• send, by a respective power-transferring element included in a first power-transfer zone of the plurality of power-transfer zones, a plurality of test power transmission signals with first values for a first set of transmission characteristics;
• in conjunction with sending each of the plurality of test power transmission signals, detect, using the signature-signal receiving circuit, respective amounts of reflected power at the first power-transfer zone, wherein the respective amounts of reflected power correspond to energy from the test power transmission signals of the plurality of test power transmission signals that was reflected outside of the near-field charging pad and returned to the first power-transfer zone;
• and
• based at least in part on the respective amounts of reflected power, determine whether (i) an authorized wireless power receiver and/or (ii) an object other than a wireless power receiver is present on a surface of the near-field charging pad that is adjacent to the first power-transfer zone.

A near-field charging pad, comprising:

• a signature-signal receiving circuit;
• a plurality of power-transfer zones that each respectively include at least one power-transferring element;
• one or more processors;
• and
• memory storing one or more programs that are configured for execution by the one or more processors, the one or more programs including instructions for:
• sending, by a respective power-transferring element included in a first power-transfer zone of the plurality of power-transfer zones, a plurality of test power transmission signals with first values for a first set of transmission characteristics;
• in conjunction with sending each of the plurality of test power transmission signals, detecting, using the signature-signal receiving circuit, respective amounts of reflected power at the first power-transfer zone, wherein the respective amounts of reflected power correspond to energy from the test power transmission signals of the plurality of test power transmission signals that was reflected outside of the near-field charging pad and returned to the first power-transfer zone;
• and
• based at least in part on the respective amounts of reflected power, determining whether (i) an authorized wireless power receiver and/or (ii) an object other than a wireless power receiver is present on a surface of the near-field charging pad that is adjacent to the first power-transfer zone.