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.

This article proposes an asymmetric magnetic coupler using the horizontal magnetic field to realize the conformal and lightweight unmanned aerial vehicle (UAV) side pickup mechanism and solve the problems of rotation misalignment and horizontal offset of UAVs. The novel structure uses multiple groups of series circular coils as the transmitting coil to construct a uniform near harness horizontal magnetic field. The solenoid structure covered with flexible magnetic material is used as the receiver, which is attached to the UAV landing gear. A 200-W prototype is produced to validate the proposed structure. The system can maintain smooth mutual inductance with a dc–dc efficiency of 90% under a ±20 mm offset and free-rotation.

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.

A wireless power transfer (WPT) system based on a hybrid topology relay is proposed to enhance mutual inductance (MI) and improve misalignment tolerance in this letter. First, the system with hybrid topology relay is proposed and the relay coil is integrated on the receiving side. Second, two adjustment factors α and β are generated by introducing the hybrid topology relay, where α is mainly used to design the equivalent MI value and β is mainly applied to adjust the fluctuation of the equivalent MI. As a result, equivalent MI can be enhanced, and misalignment tolerance can be also optimized and improved. In addition, the power transmission capability can also be improved because the transconductance gain is proportional to the equivalent MI. Finally, the experimental setup, with a power output of 3.3 kW, is constructed. The constant current output characteristic and high misalignment tolerance are verified. The results show that the dc–dc efficiency is higher than 93.05% within the 100 mm horizontal misalignment range, and the fluctuation percentage of the equivalent MI is only 4.89%.