Development of a Wireless Charging System based on LLC Resonant Converter for Underwater Drone

Autonomous underwater vehicles (AUV), also known as underwater drones, often play the important role of assisting humans to complete the tasks of ocean exploration, monitoring, and inspection of underwater infrastructure. However, the limited power supplied by batteries has restricted the navigation tasks of underwater vehicles. The development of a wireless power transfer (WPT) system for AUVs can be regarded as an important first step to realize a fully unmanned underwater vehicle. Therefore, this paper aims to develop a wireless power transfer system suitable for underwater vehicles to solve charging issues in an underwater environment. Considering the special environment with seawater as the medium, a 200W WPT charging system is implemented based on the full-bridge LLC resonant circuit combined with the loosely coupled coil and the step-down circuit. The experimental results have validated the system is able to operate in an underwater environment with the efficiency up to 90.17% in freshwater and 87.05% in seawater.