This paper proposes a bidirectional undersea capacitive wireless power transfer system (BD-UCWPT) for the autonomous underwater vehicles (AUVs). The two H-Bridge circuits are adapted in the proposed BD-UCWPT system to achieve the bidirectional power flow. The H-Bridge circuit is built based on the GaN devices. As a result, the high switching frequency, and low power loss could be reached. The two LCLC compensation networks are respectively used in the transmitter side and receiver side. The simulation work is conducted with the Ansys Maxwell, PSIM and MATLAB. In the experiments, two seawater bags are added in the middle of two metal plates of C _S1 and C _S2 to model the seawater condition, respectively. In order to verify the theory analysis, a 100W experimental BD-UCWPT system is constructed. The experiments have been conducted in air and in seawater, respectively. The simulated and experimental results are compared with each other. It shows that, with this BD-UCWPT system, the power of AUVs could flow bidirectionally. The stable operation and high efficiency of BD-UCWPT system is verified. The research work in this paper could facilitate the application of wireless power transfer (WPT) system for AUVs and other undersea devices.

Marine renewable energy (i.e., wave, tidal or ocean current, thermal gradient, and salinity gradient), can revolutionize ocean observing capabilities and marine power supply method. Under the marine environment, as the conductive feature of seawater, it has big challenge for wireless power and signal transfer under marine environment. To deal with this issue, this paper provides an undersea wireless power and data transfer system with the shared channel which powered by renewable system. The power and data could be transferred with the same channel based on the time division multiplexing theory. In one switching cycle, the power is transferred in the first half switching cycle and the data is transferred in the second half switching cycle. The data is modulated by frequency-shift keying (FSK) modulation method. The frequency for power transfer is set as 240 kHz. With the FSK modulation method, the two signal carriers’ frequencies are respectively set 10 MHz and 2 MHz. The data could be completely transferred with the high bandwidth. The glass tank experimental platform is constructed with the 35‰ salinity water. The simulated and experimental results verify the theory analysis and the calculation very well.

Underwater wireless power transfer (UWPT) system has attracted widespread attention. It has been used for power delivery for underwater equipment in the marine environment with high safety and convenience. However, the material of metal plates and the shape which will affect the high frequency alternating electromagnetic fields and the high frequency alternating electric fields for the inductive wireless power transfer (IPT) system and the capacitive wireless power transfer (CPT) system. This paper presents the effects of the hull of the autonomous underwater vehicle (AUV) on the underwater wireless power transfer system including the underwater capacitive wireless power transfer (UCWPT) system and underwater inductive wireless power transfer (UIWPT) system. The features of underwater wireless power transfer systems have been carefully studied with simulation and experimental work. The experimental water tank has been constructed with the 35‰ salinity water. The hull of AUVs has been respectively simulated and built with rectangle metal plates and curved metal plates. The original experimental data and phenomenon have been presented in this paper. The different performance of the UCWPT system and UIWPT system is provided and discussed in this paper. The comparison work with the related paper has been analyzed. This paper could be acted as the reference for designing the underwater wireless power transfer system for AUVs.

The IPT system has been studied for underwater applications such as autonomous underwater vehicles (AUVs) and subsea sensors. However, it rarely comparatively shows the performance of the IPT system in air, freshwater, and seawater. Based on the fore‐mentioned research background, this paper presents a survey of the properties of the IPT system in different mediums. Here, a 100 W power‐level experimental IPT prototype is built and tested. The resonant frequency is set at 300 kHz with a gap range from 10 to 190 mm. The comparison is focused on the efficiency, mutual inductance, coupling coefficient, coil resistance, and quality factor of the IPT system. The IPT system is placed in air, freshwater, and seawater with the same settings. What's more, the magnetic fields of coupling coils in air, freshwater, and seawater are presented in this paper. This paper could be acted as a reference to optimize the IPT system and facilitate future IPT research for underwater applications by analysing the performance of the IPT system in different mediums. The 3D Ansys Maxwell simulation of the IPT system is also given here to study the magnetic fields.

This article presents a combined control method of resonant frequency tracking and constant voltage/constant current charging mode for undersea wireless power transfer (UWPT) systems. This control method can quickly respond to the change of the resonant frequency of the system. It could solve the problem of UWPT system mismatch caused by complex marine environment with the help of a digital phase-locked loop. The circuit structure is simplified without adding any additional components or changing the topology. In addition, the constant voltage level or the constant current level of the dc output of the UWPT system is realized by adjusting the phase shift angle. The control method can adjust the resonant frequency and the dc output voltage or current without requiring an external circuit. Finally, an experimental platform of 500 W UWPT system is built to verify the theory analysis and the design. The experimental results show that this control method could track the resonant frequency well when the resonant frequency of the UWPT system is offset. At the same time, it can effectively maintain a constant output voltage or current when the load impedance of the system changes.