Parameter Identification and CC/CV Charging Strategy for Underwater WPT System Based on Phase Shift Control

Underwater wireless power transfer (UWPT) technology provides a safe and reliable charging solution for underwater equipment. While the UWPT system’s operation characteristics are closely related to the mutual inductance, parasitic parameters, and load resistance of the system, which are significantly affected by wave interference, seawater electromagnetic characteristics, and the load charging processes. Therefore, this paper proposes a parameter identification strategy and an output control strategy, both based on phase shift control, to accurately identify these parameters and achieve expected output control. Firstly, an improved mathematical model of the UWPT system is established by considering the eddy current effect of the seawater. Then, the detailed method for identifying the mutual inductance, load resistance, and parasitic parameters is presented by adjusting the phase shift angle of the secondary rectifier. Subsequently, based on the recognition results, the charging mode is switched between constant current (CC) and constant voltage (CV) based on accurate phase shift control. Finally, a kilowatt UWPT experimental platform is built up for theoretical verification. The experimental results show that the average recognition accuracy is about 98%; the CC and CV charging modes can be realized as expected, and the system efficiency can reach up to 85%.