Effect of Seawater Conductivity on Impedance Parameters of Planar Coils in Magnetically Coupled Systems

This paper focuses on the problem of coil parameter variation in magnetically coupled systems under a seawater environment. The research analyzes the effects of seawater eddy currents on the coupled coil system from different perspectives, puts forward a seawater equivalent loop circuit model, and simplifies the circuit by analyzing the effects of seawater conductivity on the self-inductance, mutual-inductance, and resistive parameters of the coils, and deduces the theories and formulas that apply to parametric analyses. The effect of seawater conductivity change on the system is verified through experiments and simulation studies, which show that seawater conductivity mainly affects the voltage and current parameters of the system by influencing the electric field around the coil, which in turn changes the equivalent resistance of the coil. The theory can provide support for the analysis of electromagnetic-inductive wireless energy transmission losses and conductivity measurements in media such as seawater.