This article proposes a free-positioning omnidirectional wireless power transfer (WPT) system with a reticulated planar transmitter, which enables multiple receivers to be powered simultaneously in arbitrary positions and orientations. The reticulated planar transmitter is equipped with four interleaved and overlapped meander coils, thus, a three-dimensional (3-D) rotating magnetic field is generated with the designed excitation current. Therefore, only a planar single-coil (such as a loop-type coil) is required to realize free-positioning omnidirectional WPT. According to the theoretical modeling of the magnetic field, the excitation current that can generate a 3-D rotating magnetic field is given. To obtain a uniform and strong magnetic field distribution, the transmitter grid width is optimized. Furthermore, an excitation current modulation strategy based on phase-shift control is presented to regulate the amplitude of the excitation current. The experimental results show that the output power is greater than 13.1 W no matter how the center of the receiver moves or rotates freely within 400 × 400 mm. When five receivers are powered simultaneously in different positions and orientations, 82.5 W total output power and 55.6% efficiency can be achieved. The experimental results demonstrate that free-positioning omnidirectional WPT can be realized with only planar single-coil receivers by using the proposed reticulated planar transmitter and its excitation current modulation strategy.

To understand the effect of chemical composition on the anti-icing properties of a nanostructured superhydrophobic surface (SHP), four SHP surfaces were prepared on glass, which was initially roughed by a radio frequency (RF) magnetron sputtering method and then modified with HDTMS (a siloxane coupling agent), G502 (a partially fluorinated siloxane coupling agent), FAS-17 (a fully fluorinated siloxane coupling agent) and PDMS (a kind of polysilicone widely used in power transmission lines). Results show that the anti-icing properties of these four SHP surfaces in glaze ice varied wildly and the as-prepared SHP surface which was modified with FAS-17 (SHP-FAS) demonstrated a superior anti-icing/frosting performance. Approximately 56% of the entire SHP-FAS remained free of ice after spraying it for 60 min with glaze ice, and the average delay-frosting time (the time taken for the whole surface to become covered with frost) was more than 320 min at −5 °C. Equivalent model analysis indicates that ΔG, defined as the difference in free energy of the Cassie–Baxter and Wenzel states, of the SHP-FAS is much lower than the other three SHP surfaces, giving priority to Cassie state condensation and the self-transfer phenomenon helping to effectively inhibit the frosting process by delaying the ice-bridging process, which is beneficial for improving the anti-frosting property. This work sheds light on and improves understanding of the relationship between anti-icing and anti-frosting properties and is helpful in making the optimum selection of a surface modifier for improving the anti-frosting/icing performances of a SHP surface.

This article is dedicated to improving the misalignment tolerance of a wireless power transfer (WPT) system using a secondary repeater. To mitigate the drop of mutual inductance when misalignment occurs, the receiver with a co-axial intermediate coil is deployed. As such, the proposed system contains three tuning ratios which correspond to the transmitting, intermediate, and receiving coils. To facilitate the choice of these parameters, an efficient tuning technique is proposed. With the proposed tuning technique, one can conveniently achieve zero voltage switching, constant voltage output, load power regulation, and suppression of load voltage fluctuation under coil misalignment. A 500-W experimental prototype is built to verify the effectiveness and superiority of the secondary intermediate aided (SIA) system. The experimental results show that within a 80-mm planar misalignment range (53.3% of the primary coil diameter), the output voltage fluctuation of the SIA WPT system is within 3%, and the peak dc–dc efficiency is 86.87%. In the vertical transfer distance range of 30–65 mm (70% of the standard transfer distance), the output voltage fluctuation is within 5%, with a peak dc–dc efficiency of 88.27%.

As an epoch-making technique, wireless power transfer (WPT) technology has been used in electric vehicle charging devices in recent years, but the electromagnetic leakage problem has always plagued numerous researchers. The traditional wireless charging systems use a solid metal aluminium plate to shield electromagnetic leakage generally. Although it has a good shielding performance, it will seriously reduce the transmission efficiency of wireless charging systems. In this paper, an aluminium plate with a series of mesh holes of different sizes is proposed to weaken the eddy current in partial areas on the plane. Therefore, without changing the maximum magnetic induction intensity of the shielded magnetic field, the influence of the aluminium plate on the electrical parameters of the wireless power transfer system is minimized, and the transmission efficiency of the system is improved. The Ansys Maxwell software has been adopted to simulate the transfer and shielding performance. Finally, the experimental results have verified that the optimized mesh aluminium plate can reduce the interference to the transmission performance of electric vehicle wireless charging system and further improve the electromagnetic environment of the system effectively at the same time.

In this article, a misalignment-adaptive wireless charging system for inspection robots (IRs) is proposed, which has autoalignment capability in the x-axis and high coupling tolerance in the y-axis. A reconfigurable secondary compensation circuit is designed to work initially in the inductor–capacitor–capacitor series (LCC-S) mode for magnetic field autoalignment, and it is then switched to LCC–LCC topology for wireless charging. The Q-coil is used in a reconfigurable coupling structure to adjust the IRs position for autoalignment, and it is also used as the compensation inductor for wireless power transfer (WPT). The DD coil in the secondary side is used to achieve high coupling tolerance capability in the y-axis. A laboratory prototype with an output current of 22 A and output voltage of 52 V is built, and practical results show that the system can achieve an alignment accuracy of ±5 mm in the x-axis, and the output current fluctuation of the system is ±3.2% when the misalignment ratio along the y-axis is 40%.

Wireless power supply system which has the advantages of flexibility, safety, reliability and high autonomy is more and more widely used in the field of UAV. Research on battery life shows that it is necessary to control the output voltage and current of WPT system to protect the UAV battery. However, the traditional control method is complicated to control and increase the secondary volume. In this paper, two sets of coupling structure are designed for UAV lightweight requirements. One of the coupling structures has constant current output characteristics, and the other can achieve constant voltage output. The control method that meets the battery charging requirements by switching the coupling structure reduces the complexity of the control algorithm. Finally, the verification is given through MATLAB simulation, and the results show that the designed system has a 8Aconstant current and 25V constant voltage output function.