Foreign substance detection method for wireless charging and apparatus therefor

A foreign object detection apparatus for detecting a foreign object placed in a charging area, the foreign object detection apparatus comprising:

• a coil unit including an inductor and a resonant capacitor and configured to convert current into flux of magnetic force;
• an inverter configured to receive and convert direct current (DC) power into alternating current (AC) power and to transmit the AC power to the coil unit;
• and
• a controller configured to control a frequency of the AC power output from the inverter and to demodulate a signal using a voltage or current of the coil unit,
• wherein the controller is configured to:
• detect an object placed in the charging area to measure a peak frequency having a maximum quality factor value,
• receive a foreign object detection status packet including a reference peak frequency from a wireless power receiver,
• determine a frequency for detecting a foreign object based on the reference peak frequency, and
• compare the peak frequency with the determined frequency to determine whether a foreign object is present.