3-What is foreign body detection for wireless car charger?

The foreign bodies here mainly refer to ferromagnetic metals. Ferromagnetic metal itself is a closed loop. When ferromagnetic metal is placed in a changing magnetic field, the magnetic flux passing through this closed loop will change, thereby generating an electric current inside the metal. This current flowing inside the metal will cause loss and cause the metal to heat up. This is the so-called eddy current effect.

When wireless charging is working normally, there is a changing magnetic field between the transmitting end and the receiving end. When metal foreign objects are placed in this magnetic field, the metal will heat up. The temperature rise to a certain level will damage the wireless charging receiver and transmitter. Foreign body detection means that when there is a metal foreign body on the wireless charging board, it needs to be detected to prevent it from becoming hot and causing unnecessary damage during the wireless charging process.