A 25 W 27.12 MHz Wireless Power Transfer system

A Class EF
₂
DC/AC inverter and a Class EF
₂
AC/DC rectifier are presented for a 25 W inductive Wireless Power Transfer (WPT) system operating at a frequency of 27.12 MHz. Class EF
₂
inverters and rectifiers are similar in construction to Class E circuits, but they contain an additional series LC circuit connected across the switch that is tuned to resonate at the second harmonic of the switching frequency. This additional resonant circuit allows Class EF
₂
inverters and rectifiers to have less voltage stresses, increased power-output capability, improved performance and reduced electromagnetic interference (EMI) than Class E circuits. Consequently, these improved features of the Class EF
₂
topology over the Class E topology can be beneficial in a WPT application.