What is foreign object detection (FOD) in wireless charging systems?

Foreign Object Detection (FOD) in wireless charging systems refers to a safety feature that is implemented to ensure the efficient and safe operation of wireless charging technology. Wireless charging, also known as inductive charging or wireless power transfer, enables devices to charge without using physical connectors or cables. It works by transferring power from a charging pad (transmitter) to a compatible device (receiver) through electromagnetic fields.

FOD is essential because it helps prevent potential hazards and damage that can occur when foreign objects are placed on the charging pad. These foreign objects can be any non-compatible items, such as metal objects, credit cards, keys, or other electronic devices that are not designed to be charged wirelessly.

Here's how FOD typically works in a wireless charging system:

Detection: 

The charging system constantly monitors the charging pad or surface for foreign objects. It uses various techniques, such as sensing changes in the magnetic field or analyzing the electrical properties of the charging area.

Identification: 

When a foreign object is detected, the system identifies it as a non-compatible item that should not be charged. This step is crucial to avoid applying power to objects that could be damaged or cause safety issues.

Indication or Shutdown: 

Depending on the system's design, there are two common approaches when a foreign object is detected. The charging pad might stop the charging process and indicate an error to the user, or it may simply refuse to initiate the charging process until the foreign object is removed from the charging area.

By implementing FOD, manufacturers ensure that only compatible devices can receive power wirelessly, reducing the risk of accidents, damage to non-compatible devices, and potential interference with the charging process. It is an important safety measure to consider when deploying wireless charging solutions in various environments, such as public charging stations or commercial products that support wireless charging.