Foreign object detection apparatus and method, and wireless charging transmit-end device

A foreign object detection apparatus, comprising:

• a controller;
• a first resonant network;
• a signal coupler;
• and
• a phase difference detector, wherein
• the signal coupler is configured to obtain a resonance current signal corresponding to the first resonant network when the first resonant network operates under action of an excitation signal, couple a preset carrier signal to the resonance current signal to obtain a coupled current signal, and transmit the coupled current signal to the phase difference detector, wherein a frequency of the preset carrier signal is the same as a frequency of the excitation signal,
• the phase difference detector is configured to extract a low-frequency signal component from the coupled current signal, determine a phase difference signal based on the low-frequency signal component, and transmit the phase difference signal to the controller, wherein the low-frequency signal component includes a frequency less than or equal to a first preset frequency in the coupled current signal, and an amplitude of the phase difference signal correspondingly indicates a phase difference between the excitation signal and the resonance current signal, and
• the controller is configured to determine, based on the amplitude of the phase difference signal, whether a foreign object exists in a detection area corresponding to the first resonant network.