Analysis of the Mutual Impedance of Coils Immersed in Water

Abstract

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.

Optimization of Transfer Quality Factor of Limited-Size Coils for Series-Series Compensated Inductive Power Transfer System

“…The mutual inductance is measured by the in-phase and the opposing-phase connections of primary and secondary coils. When the two coils are connected in the same phase, the inductance L s can be measured, and when the two coils are connected in opposite phase, the inductance L o can be measured, and mutual inductance can be obtained by (L s − L o )/4 [25]. In order to compare the performance of the optimization method proposed in this paper, we compare the performance of three kinds of coils.…”

A Novel Conformal Coil Structure Design of Wireless Power Transfer System for Autonomous Underwater Vehicles

“…The AC resistance of transmitting and receiving coils is 1.22 Ω and 0.66 Ω, respectively. The mutual inductance of the coils is measured by the in-phase and the opposing-phase connections [20]. Figure 7 depicts the variation curve of the mutual inductance with rotational misalignment, radial, and axial eccentricity.…”

A Novel Modulation and Demodulation Method Based on Binary Frequency Shift Keying for Wireless Power and Data-Parallel Transmission

“…Litz wire with 0.1 mm × 100 strands is selected for coil processing in order to reduce the AC resistance. The mutual inductance between the two coils is obtained according to the in-phase and the opposing-phase connections of the coils [20], which is measured by an LCR-8205 impedance analyzer. The key parameters of the system are listed in Table 1.…”