Model of a wireless charging system operating in seawater under rough sea conditions. P. 2

This study focuses on the development of a comprehensive mathematical and computational model for a wireless battery charging system designed for autonomous underwater vehicles operating in seawater under rolling conditions. The research is motivated by the lack of existing models that account for the combined effects of varying coil alignment and the characteristics of a highly conductive medium. Experimental results are presented for a 150 W wireless charging system featuring a series LC topology intended for marine environments. The experiments aimed to validate the comprehensive mathematical and computational model—based on the mathematical description provided in the first part of the paper—and to assess the impact of the conductive medium (freshwater and seawater) on the system's energy characteristics. The experimental setup, utilizing multi-layer coils, and the measurement methodology are described. A comparative analysis was conducted between the system's amplitude-frequency characteristics in air, freshwater, and seawater and the corresponding simulation results. Parameters for the equivalent circuit, accounting for eddy current losses, are identified using a successive approximation method. It is demonstrated that model M2—which accounts for these losses via equivalent resistances—shows strong agreement with experimental data (with a root-mean-square error of no more than 5%), whereas the influence of parasitic capacitances within the 90–130 kHz operating frequency range is negligible. The study confirms the necessity of accounting for the nonlinearity of semiconductor components to accurately describe frequency-domain processes. The results validate the developed model and demonstrate its suitability for predicting system performance under actual operating conditions.

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