De'AN Wang

The collaborative execution of tasks by unmanned underwater vehicles (UUVs) in a swarm has gradually become one of the typical working modes of underwater unmanned equipment. However, there are few efficient solutions to the autonomous power supply issue of the swarm UUVs. In this paper, a novel expandable O4DO-type modular magnetic coupler is presented for swarm UUV wireless power transfer systems, which exhibit superior performance in terms of high efficiency, conformality, reliability, receiver power density, anti-misalignment tolerance, modularity, and scalability. The design and optimization methodology of the proposed O4DO-type magnetic coupler are thoroughly elaborated, followed by comprehensive experimental validation under various operational conditions. Experimental results demonstrate that the proposed swarm O4DO magnetic coupler enables simultaneous wireless charging for multiple UUVs in docking alignment, achieving a system efficiency exceeding 93%. Moreover, the system supports flexible scalability based on the number of UUVs and incorporates fault-tolerant capabilities, ensuring long-term underwater endurance for swarm operations.

In recent years, the application of nanocrystalline materials in wireless power transfer systems has been continuously investigated. However, due to their significantly higher conductivity characteristics than ferrite, they can trigger additional eddy current losses and attenuate the transmission efficiency of the system. This article presents a novel diagonal-laminated Fe-based nanocrystalline magnetic structure, which significantly reduces the additional eddy current loss of typical flat-laminated nanocrystalline structures and possesses excellent shielding effects. The modeling and analytical calculations of magnetic shielding energy efficiency and eddy current losses are performed and discussed in conjunction with magnetic reluctance modeling and finite element simulations. The superiority of the proposed core structure is verified by comparative experiments with five different magnetic pads prototypes of wireless power transfer couplers. Results show that the shielding effect is almost comparable to that of the ferrite pads when transmitting 3 kW power. The system efficiency is higher than 93.4%. Specifically, compared with the ferrite pads, the proposed structure reduces the core weight and volume by about 15.1% and 31.9%, respectively, realizing the lightweight design and efficient operation of the system.

Flexible soft magnetic materials represented by nanocrystalline have been widely used in magnetic couplers of wireless power transfer systems due to their superior electromagnetic properties and mechanical flexibility in recent years. However, the high conductivity characteristics and thinner material unit thickness of nanocrystalline materials expose additional issues. This article first proposes a general modeling and analytical calculation method for shielding energy efficiency and loss of the nanocrystalline laminated magnetic core structure. Then, a novel hybrid multi-permeability Fe-based flexible nanocrystalline laminated ribbon magnetic structure is proposed. By multi-objective optimization of the permeability, the additional eddy current loss has been significantly reduced. In addition, the transmission performance of the proposed magnetic structure is compared with five similar structures in experiments. Results show that the system transmission efficiency is higher than 93.8% when transmitting 3 kW power and has a superior electromagnetic shielding effect. The proposed structure leads to a significant reduction in weight and volume, which is conducive to the lightweight design and efficient operation of the system. The novel structure achieves a uniform distribution of magnetic flux density while enabling effective thermal management and electromagnetic compatibility of the magnetic coupler, which contributes to the long-term reliable operation of the WPT system.

Magnetic coupling resonance wireless power transfer (WPT) technology provides an effective solution to the range anxiety of the autonomous underwater vehicle (AUV). However, the irregular disturbance of marine currents poses great challenges to the engineering and practical application of underwater wireless power transfer technology. In this paper, a novel discrete solenoid magnetic coupler with wide range anti-misalignment tolerance is proposed by using the ingeniously designed uniform space electromagnetic field to suppress the power efficiency fluctuation issue in the actual working conditions of the AUV-WPT system. The design and optimization process of the proposed structure are elaborated in detail, and a 3-kW experimental prototype is constructed to verify the anti-misalignment tolerance superiority of the scheme. The proposed coupler has a conformal structure, which will not change the hydrodynamic characteristics of the AUV and the docking station. Experimental results show that within the range of [-100 mm, 100 mm] axial misalignment and 360° rotational misalignment, the system efficiency remains above 90%, with less than 0.5% efficiency fluctuations. Besides, the proposed coupler has significant EMC advantages compared to similar solenoid structures, which can greatly improve the space utilization inside the AUV cabin and have excellent engineering application prospects.

This study investigates the dynamics of wireless power supply technology under rotation and its system redundancy, aiming to design a redundant, rotating wireless power supply system. In order to satisfy specifications of redundancy and fault tolerance, the circuit design of the wireless power transmission system was developed, and a planar three-sector coil coupling mechanism was designed; finally, the stability and power output characteristics of the system were assessed under static and dynamic working conditions, and the results show that the maximum output power of the system can reach 3 kW and the efficiency is more than 91% under both static and dynamic working conditions. The study improved the rotating wireless charging system’s efficiency, which improves the energy utilization efficiency.

Magnetic coupling resonance wireless power transfer technology is one of the effective ways to solve the energy supply problem of autonomous underwater vehicles. As the most critical component in an underwater wireless power transfer system, the magnetic coupler largely determines the energy transfer capability and marine environment adaptability. This article proposes a novel ID-shaped magnetic coupler with a pendulum-type receiver, which has characteristics of compact structure, lightweight, enough misalignment tolerance, and high receiver power density. The design and optimization flow of the magnetic is given in detail in this article, and an experimental prototype is constructed to verify the proposal. The receiver weighs only 746 g, yet it can deliver over 3 kW at 95.985% dc–dc efficiency when fully aligned. Especially the proposal achieves stable output in the range of rotational and axial misalignment of [−30 mm, 30 mm], with a system efficiency consistently above 95% and efficiency fluctuations below 1%.

The magnetic coupling resonant wireless power transfer (MCR-WPT) system is considered to be the most promising wireless power transfer (WPT) method because of its considerable transmission power, high transmission efficiency, and acceptable transmission distance. For achieving magnetic concentration, magnetic cores made of magnetic materials are usually added to MCR-WPT systems to enhance the coupling performance. However, with the rapid progress of WPT technology, the traditional magnetic materials gradually become the bottleneck that restricts the system power density enhancement. In order to meet the electromagnetic characteristics requirements of WPT systems, high-performance Mn-Zn and Ni-Zn ferrites, amorphous, nanocrystalline, and metamaterials have been developed rapidly in recent years. This paper introduces an extensive review of the magnetic materials of WPT systems, concluding with the state-of-the-art WPT technology and the development and application of high-performance magnetic materials. In addition, this study offers an exclusive reference to researchers and engineers who are interested in learning about the technology and highlights critical issues to be addressed. Finally, the potential challenges and opportunities of WPT magnetic materials are presented, and the future development directions of the technology are foreseen and discussed.

The underwater wireless power transfer (UWPT) technology provides a feasible way to solve the problems of the traditional power supply method of the autonomous underwater vehicle (AUV). The magnetic coupler is the most essential component in the wireless power transfer system. Its configuration determines its applicable scenarios, and its parameter design and optimization will directly affect the system's overall output power and efficiency. In this article, an arc-shaped underwater wireless power transfer magnetic coupler is proposed, which is suitable for AUV's curved shell. Especially, the proposed novel magnetic coupler utilizes Fe-based nanocrystalline alloy soft magnetic material as the magnetic core. Both volume and weight of the receiver are reduced compared with the traditional Mn-Zn ferrite material. Fe-based nanocrystalline alloy material provides a novel design idea for the magnetic coupler on electrical equipment with special-shaped shell due to its flexibility. A prototype of the UWPT system for 320 mm diameter AUV is built, and it can transfer 3 kW power in the experiment with a dc–dc efficiency of 91.9% at the forward maximum output power point. Compared with the structure with ferrite core, the volume of the proposed structure is reduced by 41.1%, and the weight is reduced by 42.6%, so that the expected effect has been achieved.