The wireless power charging system is implemented to apply
the presented power transmitter. The system is designed to
charge a 12V@20Ah LiFePO4 battery which is used for a
walking-assistance vehicle. The output power control function is
implemented by using the 424MHz FSK communications
between the power transmitter and the receiver in order to
maintain the power transmission efficiency. The average system
DC to DC efficiency is about 50% during the wireless charging.