Maximum Efficiency Tracking for Multitransmitter Multireceiver Wireless Power Transfer System on the Submerged Buoy

The wireless power transfer (WPT) system is widely applied in the underwater environment. A multitransmitter multireceiver WPT system is proposed in this article for the application of the submerged buoy, and numbers of beacons can be charged at the same time to send more data. Both series and parallel connection structures of several coils are analyzed in detail. In order to increase the system efficiency at ultracapacitors charging process, a maximum efficiency tracking with a primary current controller and an optimal resistance controller is studied and designed. All mentioned above analyses are verified in a three-receiver WPT system prototype. When ultracapacitors are charged from 10 to 25 V, the system efficiency is achieved at almost 70.5%, and the charging voltage of all three receivers can be stabled.