Design and optimization of air core spiral resonators for magnetic coupling wireless power transfer on seawater

Abstract

This paper focuses on the design of high quality spiral resonators for maximising wireless power transfer efficiency between an AUV and an underwater docking station. By using 3D electromagnetic simulations and numerical analysis, the relevant parameters for quality factor computation are extracted. The impact of different variables on a spiral resonator's quality factor is assessed, allowing to conclude on the optimum design parameters to achieve optimum efficiency on the power transmission through magnetic coupling. This work will contribute to enable the development future AUV wireless charging systems, which will allow for an improvement of AUV's range and endurance while ensuring lower operational costs.

Assessment of design trade-offs for wireless power transfer on seawater

“…At f = 194.6 kHz the quality factor of a single inductor was measured as Q = 68.4, using the LCR meter. After connecting the parallel capacitor to achieve resonance, a quality factor of Q = 58.4 was measured indirectly from the input impedance as described in [10], which is lower than the expected as capacitors have Q = 400 [11]. By unloading the resonators with series capacitors as explained in subsection III-A, we measured two |S 21 | peaks on the VNA at f 1 = 122.4 kHz and f 2 = 158.1 kHz, which resulted in a coupling coefficient of k ≈ 0.25 for a gap of 4 cm.…”

“…and the series-series resonance becomes Using the ABCD matrices of equations (10), (11), (12) and combining them on equation 4, at the resonant frequency where X C = X L , the efficiency of a series-series compensated system is given by…”

“…The gap between coils is estimated to be 4 cm, which after applying equation 20gives a nominal coupling factor of k = 0.294. Additionally, according to [9] and [10], quality factors around 100 were achieved for helical inductors and spiral coils, respectively. For this reason we use a nominal value for the quality factor of the LC resonator of Q = 100.…”

Wireless Power Transfer for Unmanned Underwater Vehicles: Technologies, Challenges and Applications

“…Here, a solenoid transmitter was tested with a dual planar receiver, achieving an efficiency of 85% for a 401 W power transfer without misalignment. Furthermore, many other planar and coaxial systems that achieved power transfer values below 100 W or did not provide enough information to analyze their parameters can also be found in the literature [159,[200][201][202][203][204][205][206]. Additionally, some other works present comparisons between planar topologies [207] and planar and coaxial topologies [208].…”

Experimental Investigation of Transfer Characteristics of Midrange Underwater Wireless Power Transfer

“…Based on these two points, many solutions have been proposed. A method for designing high quality spiral resonators with transmission efficiency up to 95% is suggested in [14]. In [15], targeting the two main problems of seawater attenuation and resistance, a lightweight self-locking coupling structure on the receiving side is proposed to improve the coupling coefficient to resist ocean current interference.…”