Design of a Capacitive Coupler for Underwater Wireless Power Transfer Focused on the Landing Direction of a Drone

Abstract

This paper presents the design of a capacitive coupler for underwater wireless power transfer focused on the landing direction of a drone. The main design feature is the relative position of power feeding/receiving points on the coupler electrodes, which depends on the landing direction of the drone. First, the maximum power transfer efficiencies of coupled lines with different feeding positions are derived in a uniform dielectric environment, such as that realized underwater. As a result, these are formulated by the coupling coefficient of the capacitive coupler, the unloaded qualify factor of dielectrics, and hyperbolic functions with complex propagation constants. The hyperbolic functions vary depending on the relative positions and whether these are identical or opposite couplers, and the efficiencies of each coupler depend on the type of water, such as seawater and tap water. The design method was demonstrated and achieved the highest efficiencies of 95.2%, 91.5%, and 85.3% in tap water at transfer distances of 20, 50, and 100 mm, respectively.

Capacitive Wireless Power Transfer System with Misalignment Tolerance in Flowing Freshwater Environments

“…The particular point is the frequency characteristic of kQ product under freshwater; k means the coupling coefficient in the coupler and kQ product means the product of k and Q factor. Furthermore, an efficiency of over 85% was achieved at a distance of 100 mm, by adjusting the relative position of the power feeding/receiving points on the coupler electrodes [21]. From the above, it can be concluded that the performance of the capacitive coupler is as good as that of the inductive coupler in freshwater environments, such as rivers and dams.…”

“…The Z-matrix elements can be organized into a simple form by defining A-D as ( 5)- (8), respectively [21].…”

A Novel Coupler of Capacitive Power Transfer for Enhancing Underwater Power Transfer Characteristics

“…Electronics 2024, 13 where A represents the surface area of the metal plates, d1 is the thickness of the insulating layer, d2 is the thickness of water, ε0 is the vacuum's dielectric constant, εr(mica) is the insulation layer's relative dielectric constant, and εr(water) is the water medium's relative dielectric constant. In this way, the equivalent capacitance Ceq1 for a single pair of metal plates in water medium could be calculated as (…”

“…Therefore, it is important to conduct research on capacitive power transfer (CPT) in order to ascertain its viability for underwater applications [9]. The field of CPT has also seen extensive research efforts, leading to numerous research findings such as electric vehicles [10][11][12], underwater vehicles [13][14][15], and electric ship charging [3,16].…”