Analysis of the Mutual Impedance of Coils Immersed in Water

Magnetic induction communication and wireless power transmission based on magnetic coupling have significant application prospects in underwater environments. Mutual impedance is a key parameter particularly required for the design of the systems. However, mutual impedance is usually extracted from measurements when the coils are processed, which is obviously not conducive to the system optimization in the design phase. In this paper, a model of the mutual impedance of coils immersed in water is established. The magnetic vector potential is expressed in the form of series by artificially setting a boundary, and then the mutual impedance calculation formula of the coils immersed in water is derived. In the analysis, the effect of the conductivity of water, the excitation frequency, and the number of turns of the coils are mainly taken into account. In addition, the variation of the mutual impedance of coils in air and water with axial displacement is also compared. The models can be used to analyze the coil coupling characteristics in the presence of conductive medium, which is helpful for the design process.

Automated summary

This paper established a model of the mutual impedance of coils immersed in water, analyzing the effects of the conductivity of water, excitation frequency, and number of turns of the coils on mutual impedance, and comparing the variation of mutual impedance of coils in air and water with axial displacement. The models provided are helpful for analyzing coil coupling characteristics in the presence of conductive medium during the design process.