Critical and Parasitic Parameters Identification and Frequency Regulation Strategies for UWPT Systems

For underwater wireless power transfer (UWPT) systems, one of the most difficult problems is how to accurately identify the mutual inductance, load resistance, and parasitic parameters of the system. That is because these parameters will be influenced by the electromagnetic properties of seawater, the wave disturbance, and the charging process. And the system performance will be impacted correspondingly. Therefore, this article presents a new parameter identification and frequency regulation strategy for the UWPT systems. First, an improved mathematical model of the UWPT system is established by considering the eddy current effect in the primary, secondary, and mutual inductance branches. Then, the parameter identification strategy of mutual inductance, load resistance, and parasitic parameters is proposed by a simple frequency regulation method based on the proposed UWPT system model. Subsequently, with the identified results, the frequency splitting phenomenon and frequency regulation strategy are studied to further improve the system's performance. Finally, a 600 W UWPT setup is built up to verify the theoretical analysis, and the experimental results show that the average identification accuracy can reach 97.3%, and the maximum output power can be realized with nearly constant system efficiency.