A novel magnetic coupler (MC) with cross-coupling mode is proposed in this article, which has merits of fit-to-surface and lightweight in receiver, and supports stable and efficient charging for autonomous underwater vehicles (AUVs). The proposed magnetic structure employing an arc bipolar transmitter and a compact dipole-coil-based receiver utilizes horizontal flux to establish strong and stable coupling against three-dimensional misalignment; the MC structure is constructed and optimized according to the magnetic field distribution characteristics. The influence of geometric parameters on the MC's performance is obtained based on ANSYS Maxwell simulation, with which the parameters of MC are optimized. In order to fully verify the performance of the designed MC, an AUV wireless charging system circuit is also developed. A wireless charging system prototype is built and tested with a 600 g receiver, and it can deliver 1 kW at a dc-to-dc efficiency of 95.1%. The experimental results under various operating conditions indicate that the proposed MC is viable and can be used for charging the AUVs.

Compact design in receiver and misalignment tolerance are two basic considerations for practical applications of wireless power transfer (WPT) in unmanned aerial vehicles (UAVs). To balance these two requirements, a novel magnetic design with the composite interval-acted parallel- & vertical-flux throw, orthogonal two-dimensional flux pick-up, and power-flow summed output is proposed in this letter. The resulting magnetic structure includes a target-shaped transmitter and two quadrature receivers, and the transmitter consists of four annular-type coils which are magnetized in a bipolar mode, making it possible to form a magnetic field with a parallel- and vertical-flux complementary distribution. Moreover, by integrating two orthogonal receiving coils into one receiver, a stable summed output current can supply the UAV onboard load with only a small size receiver. A UAV WPT prototype is established based on the proposal. The results show that the prototype can deliver 325 W with a system efficiency of 86%, and especially the variation of the output current is within ±0.76 A for different landing positions and directions. The overall system efficiency is from 87.3% down to 83.1%.

Design and fabrication of a wireless charging system which includes a wireless charging base station and an unmanned aerial vehicle (UAV) with wireless charging capability is proposed for enlarging the UAV's working range. First, an optimized magnetic coupler featuring with an orthogonal magnetic structure with a soft magnetic core in receiver is proposed to ensure high efficiency and low leakage magnetic flux interference. Second, a wireless charging circuit topology and a closed-loop power controller implemented on the primary-side are designed and analyzed in detail to maintain constant current/ constant voltage charging for the UAV. Then, a wireless charging station with position correction aid device is developed, which can achieve high-precision alignment. A prototype of the UAV wireless charging system with the proposed magnetic structure, primary-side control and position correction are built and tested. Experimental results show that the fabricated wireless charging system can deliver 87.4 Watts at a DC-to-battery efficiency of 87.3%, and the system is adapted autonomous charging of UAV.

This letter proposes a novel capacitive power transfer system for the unmanned aerial vehicles (UAVs) with lightweight in receivers and robust misalignment tolerance characteristics. The design and analysis of a reconfigurable capacitive coupler are presented at first. The transmitter adopts four rectangular copper plates, which can be reconfigured according to the landing positions and directions. The receiver includes two hollow cylindrical copper-foil sleeves wrapped at the bottom of UAV landing gears, thereby leading to the adaption of the UAV's structure and the tolerance to lateral-, longitudinal-, and angular misalignment. Then, simulation and prototype experiments are carried out to verify the proposal. The results show that the prototype has low leakage electric flux at the UAV fuselage and can deliver 212.1 W with a dc-to-dc efficiency of 82.5%. Especially the proposal allows UAV to be powered within ±0.76 A of output current variation for different landing positions and directions, and the system dc-to-dc efficiency variation is within ±1%.

Design and fabrication of a practical wireless charging system, which includes a submerged docking station and an autonomous underwater vehicle (AUV) with power pick-up capability, is proposed to recharge an AUV safely and autonomously. First, a docking design, based on a funnel-type docking station, an acoustic and optical combination guiding method and a position locking mechanism, is presented to smoothly dock the AUV and eliminate the dynamic disturbance during the charging process. Then, a novel magnetic structure with an overlapped direct-quadrature transmitter and a dipole receiver is proposed. The two-layer transmitting windings, decoupling each other, form a constant amplitude traveling wave under the space-time coordination mechanism for suppressing output fluctuation with misalignments. Moreover, a practical wireless charging circuit, based on current doubler, is developed, modeled and analyzed. Finally, an experimental prototype is constructed to verify the proposal. The system can deliver 1.2 kW to the load with a system efficiency of 90%, and especially the proposal achieves stable output in the range of rotational misalignment of [-30°, 30°] and axial misalignment of [-30 mm, 30 mm].

This letter develops a wireless charging system based on a novel orthogonal magnetic structure and primary-side power control to simplify the structure and reduce the weight of on-board pick-up for recharging the unmanned aerial vehicles (UAVs). The novel magnetic structure has a polarized transmitter with a flat U-type core and a perpendicular air-cored receiving coil, guaranteeing the magnetic flux operation space away from UAV body by coil structure itself and also reducing the weight of magnetic receiver. The power flow to the battery is controlled by the primary-side based on charging current and voltage feedback by pick-up. Simulations based on ANSYS Maxwell and experiments are carried out to validate the proposal. The weight of magnetic receiver is 130g. And the system can deliver 500W with a DC-to-Battery efficiency of 90.8%, meanwhile 10A constant current/50V constant voltage charging for 12S lithium-ion battery is achieved by the closed-loop system.