Wireless charging, also known as inductive charging, utilizes transformer coupling of two inductor coils to transfer energy from a charging station to a wireless device. The charging station power supply radiates energy that is received by the wireless device and either runs the device directly or is stores the energy in a battery through a battery charger circuit.

The charging station is an inductive charger that includes a coil referred to as the sender coil. High frequency AC is pumped into the coil by the charger.  By placing the wireless device’s receiver coil in close proximity to the sender coil, a transformer is formed and a current is induced in the receiver coil. The ability of the receiver coil to couple depends upon the material between the two coils and the distance between them. Distance can be increased by choosing a receiving coil with resonant characteristics at the AC frequency.

The main advantage of wireless charging is that no conductive connectors are required. This allows the charging connection to be insulated – making for safer devices when used in medical or hazardous environment applications. Insulated connections also prevent corrosion effects on contacts. There is improved durability as connector/contact failure is not required. The main disadvantage is very low efficiency and potential for heating occurring. Charging is slower because less power is coupled across the connection. Wireless charging also requires more expensive components to be used.