Parasitic Parameter Extraction and Analysis of Coupling Device in Underwater IPT System

This paper investigates the parasitic coupling capacitance of planar spiral coils in underwater inductive power transfer (IPT) systems. The formation mechanism of parasitic capacitance in seawater is analyzed, and a refined equivalent circuit model alongside its corresponding analytical formulations is established. Through COMSOL multiphysics simulations and experimental verification, it is demonstrated that the magnitude of parasitic capacitance in seawater remains independent of the seawater's dielectric constant, being primarily determined by the insulation layer. Furthermore, the inherent structural asymmetry of planar spiral coils is found to exacerbate impedance imbalance within the common-mode loop. These findings provide a theoretical foundation for common-mode noise suppression in underwater IPT systems.