Multi Parameter Identification and Battery Charging Control of UWPT System Based on Primary Measurement

Underwater wireless power transfer (UWPT) technology offers an effective solution to the energy constraints of underwater vehicles by enabling in-situ and real-time energy replenishment. However, the UWPT system circuit becomes more complex than the aerial counterpart due to eddy current effects. Furthermore, the roll motion of vehicles and seawater flow cause misalignment between the underwater vehicle and the energy base station, which disturbs system parameters and significantly reduces efficiency. In this paper, a two-layer online parameter identification method is proposed based on an improved circuit model that accounts for eddy current effect. Through primary port information measured and impedance calculation, the coil self-inductance, mutual inductance, load resistor, roll offset angle, equivalent inter resistance and phase offset in mutual inductance branch are predicted with average error of 0.49%, 1.06%, 0.90%, 0.23°, 0.08Ω, 0.95°. Based on identification results, constant voltage or constant-current charging is achieved with an average error of 0.89% and 1.12% demonstrated by experimental results.