In this paper, a novel simultaneous wireless power and data transfer (SWPDT) system is proposed for underwater wireless sensor networks. A pair of coils is used to establish forward power transfer and bidirectional data transfer links based on coupled magnetic resonance. While transmitting power to the load, the forward power waves are also used as the carrier for data transfer, thereby avoiding the use of an additional carrier source on the power transmitter-side. An improved double-LCC double-CLC topology is presented to achieve both impedance matching and wave filtering of the SWPDT system in full-duplex mode, instead of using additional wave trappers, transformers or tap coils. Compared with previous works, the proposed system can simultaneously achieve high power gains, low mutual interference and simple circuit structure. Moreover, to deal with the conflicts between the power gains and the bandwidths of the channels, an improved multi-objective optimization method is proposed for the SWPDT system. Using this method, the Pareto optimal solutions of the system parameters can be found and the comprehensive performance of the SWPDT system can be further improved. Finally, an experimental prototype is established, which achieves full-duplex wireless power and data transfer, with a maximum load power of 23.1W, a forward data transfer rate of 20kbps and a backward data transfer of 300kbps. There is almost no interference between power and data transfer. The experimental results show that the proposed SWPDT system has good application prospects in underwater sensor node charging and full-duplex communication.

One of the greatest challenges to power embedded devices using magnetically coupled resonant wireless power transfer (WPT) system is that the amount of power delivered to the load is very sensitive to load impedance variations. Previous adaptive impedance-matching (IM) technologies have drawbacks because adding IM networks, relay coils, or other compensating components in the receiver-side will significantly increase the receiver size. In this paper, a novel frequency-tracking and impedance-matching combined system is proposed to improve the robustness of wireless power transfer for embedded devices. The characteristics of the improved WPT system are investigated theoretically based on the two-port network model. Simulation and experimental studies are carried out to validate the proposed system. The results suggest that the frequency-tracking and impedance-matching combined WPT system can quickly find the best matching points and maintain high power transmission efficiency and output power when the load impedance changes.

This article proposes a single-transmitter multi-receiver wireless power transfer (STMR-WPT) system, which uses a cross-overlapped bipolar coil as the transmitter and multiple square unipolar coils as the receivers. By using this structure, the magnetic field of the system can be adjusted to accommodate different coil misalignment conditions. In addition, the proposed system uses C-CLCs networks to achieve separate load power allocation. Thus, relay coils, complex multi-frequency transmission channels and multiple independent power supplies can be avoided. A mapping impedance-based circuit model was established to analyze the characteristics of the system, and then a single-frequency power allocation method was presented. Through this method, the STMR-WPT system can achieve load power allocation at any specified ratios under different mutual inductance and load impedance conditions. Finally, an experimental STMR-WPT system was built. The side lengths of the transmitter and receiver coils are 400 mm and 160 mm, respectively. The measurement results indicated that when the lateral or longitudinal coil misalignment varies within the range of 0~200 mm, the coupling coefficient decreases by a maximum of 6% compared to the initial value, and when the angular coil misalignment varies within the range of 0~90 degrees, the coupling coefficient decreases by a maximum of 22% compared to the initial value. In four different power allocation scenarios, the experimental STMR-WPT system successfully achieved the expected power allocation goals.

Magnetically-coupled resonant wireless power transfer (MCR-WPT) technology is one of the most promising technologies to power embedded sensors. In many practical situations, embedded sensors are located in a metal environment. The nearby metal materials will affect the performance of the MCR-WPT system. In this paper, the equivalent circuit model of the MCR-WPT system in metal environment is established and the factors affecting the transmission efficiency is analyzed. Then, simulation analysis is performed using Maxwell software and Simplorer software. Two cases are considered in the simulation study: the coil is close to a metal plate and the coil is close to a metal shaft. Simulation results show that metal materials will change the coil inductance and interfere with the magnetic field distribution of the MCR-WPT system, which in turn affects the transmission efficiency of the system.

In the field of uncrewed aerial vehicle (UAV) wireless charging, inductive power transfer (IPT) and capacitive power transfer (CPT) have become the two main technical approaches. However, existing single-topology systems still face significant challenges. This article proposes a hybrid IPT-CPT wireless power transfer (WPT) system to address key limitations of lightweight design and landing misalignment tolerance. First, a hybrid coupler is designed, with CPT serving as the main energy transfer channel. By reusing the compensation inductor as the coupler of IPT, the integration level of the system is improved. Then, a frequency-variable reconfiguration strategy with single-switch control is introduced to enable constant current (CC) and constant voltage (CV) output modes. Furthermore, a modified MOEA/D algorithm is employed to co-optimize electromagnetic parameters, balancing transmission efficiency and output power. Experimental results demonstrate that the system delivers 218.8 W with 86.38% efficiency in CC mode at 750 kHz and 216.6 W with 81.39% efficiency in CV mode at 778 kHz. The system exhibits strong misalignment tolerance, maintaining stable operation within $\boldsymbol{\pm}$25~mm (x-axis) and $\boldsymbol{\pm}$100 mm ($y$-axis) offset ranges.

Metasurface provides a promising solution to address the efficiency-distance-safety challenges in magnetic coupling resonant wireless power transfer (MCR-WPT) systems through subwavelength electromagnetic field manipulation. Current research primarily focuses on single-frequency operation or mostly MHz-band applications. It lacks theoretical and simulated studies of kHz band, let alone the cross-frequency band (both kHz and MHz simultaneously). In this article, a cross-frequency metasurface in the MCR-WPT system has been proposed. First, an equivalent circuit model of a cross-frequency metasurface has been derived. Then, EMF analysis of WPT system based on the cross-frequency metasurface has been presented. Particularly, an improved dual-population cooperative evolutionary algorithm has been employed to optimize both cross-frequency mu-negative (CF-MNG) and cross-frequency mu-near-zero (CF-MNZ) metasurfaces. Finally, the cross-frequency metasurface exhibits excellent performance on efficiency improvement and EMF leakage reduction in MCR-WPT system. The system with CF-MNG loading achieved nearly double the transfer efficiency at both 350 kHz and 6.78 MHz frequencies. Additionally, the decline of leakage electromagnetic field (EMF) with CF-MNZ metasurface can reach up to 2.42 and 6.51 dB at two frequencies, respectively. Therefore, this article not only provides significant guidance for low-frequency metasurface design but also offers potential for future applications in simultaneous power and information transfer systems.