A 95% efficient inverter with 300-W power output for 6.78-MHz magnetic resonant wireless power transfer system

We developed a high-power Class-E inverter for a 6.78-MHz magnetic resonant wireless power transfer system. The inverter consisted of six synchronized coupled low-power inverters; the outputs were combined after the corresponding matching circuit. We attained a drain efficiency of 94.6% at the power output of 315 W. In addition, we demonstrated a wireless power transfer system consisting of the Class-E inverter, a pair of magnetic resonant coils 200 mm in diameter separated at an air-gap distance of 42 mm, and a diode bridge rectifier. The system achieved a dc-dc efficiency of 84.7% at a power output of 301 W.