Power Transmitter Design for Underwater WPT

The present work addresses the development of a power inverter, specifically designed for underwater wireless power transfer (WPT) by means of magnetic resonant coupling, having salt water as the transmission medium. Series capacitors are used both at the primary and secondary sides of the coupled coils, but with the operating frequency defined above resonance. The design makes use of the impedance of load and resonant coupling coils to establish class-DE conditions in a full-bridge inverter. Experimental WPT results with salt water separating the primary and secondary sides demonstrated dc-to-dc efficiencies in the range of 80 to 86 percent, i.e. taking into account rectification at the secondary side and losses in water, achieving output power levels in the range of 20 to 80 Watt at operating frequencies between 150 and 210 kilohertz.