Huimin Gao

Simultaneously enabling wireless charging for multiple electronic devices is a distinctive advantage of wireless power transfer (WPT). Nevertheless, the development of dual-receiver WPT systems is constrained by several challenges, including undesired cross-coupling effects, suboptimal spatial utilization, complex control strategies, and insufficient system stability. To overcome the limitations, this article develops a multipolarity decoupled four-coil WPT system with constant voltage (CV) and constant current (CC). The proposed system suppresses undesired cross-coupling to negligible levels, thereby reducing the system complexity. In addition, the compensation network can be designed in a straightforward manner, providing improved design flexibility. A detailed mathematical derivation is presented to rigorously demonstrate the load-independent CV and CC output characteristics. Meanwhile, the inverter can achieve zero phase angle (ZPA), thereby improving the power factor of the WPT system. In addition, the multipolarity decoupled mechanism of the four-coil magnetic coupler is analyzed in detail theoretically. Finally, an experimental prototype is built and tested. The experimental results demonstrate a strong agreement with the theoretical analysis, ensuring load-independent CV and CC outputs of 68 V and 3.5 A, respectively. The system achieves a measured peak efficiency of 85.97%.

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.

With the rapid advancement of wireless power transfer technology (WPT), the requirement for stable power transmission across spatial domains has become increasingly prominent. To address this challenge, this paper proposes a multi-degree-of-freedom (multi-DoF) anti-misalignment WPT system based on Parity-Time (PT) symmetry technology. The system can maintain stable output by integrating the designed 3D orthogonal coupling mechanism with PT symmetry theory and employing a dynamic switching strategy for the operating coil based on frequency detection. Furthermore, an improved NSGA-II algorithm is introduced for multi-objective optimization of structural parameters to ensure sustained over-coupled operation under multi-DoF misalignment conditions. Experimental results show that the proposed system can autonomously track the characteristic frequency. Moreover, the system can maintain 16.12W output power and 62.6% transmission efficiency within a 50 cm cubic workspace under multi-DoF misalignment conditions, and enable stable omnidirectional energy transfer.

Quasi-static cavity resonance wireless power transfer (QSCR-WPT) technology can achieve pervasive power delivery in room-scale range. The coupling model of the system has been established by several approaches. However, the accuracy of mathematical model is seriously limited due to the lack of direct measurement of the equivalent parameters of the cavity, which hinders the analysis and design optimization of the system. Additionally, the coupling model is difficult to analyze key characteristics, such as the voltage and current. To address this issue, a hybrid parameter extraction methodology is presented firstly and it combines long short-term memory (LSTM) networks with nonlinear least squares (NLS) optimization. Specifically, approximate equivalent circuit parameters are obtained using an LSTM network from the input impedance spectrum data. These parameters serve as initial values for the NLS algorithm, which then performs precise regression to yield precise circuit parameters. Thus, system performance can be represented and analyzed clearly. Experimental results demonstrate that the implemented methodology achieves 95.78% voltage prediction accuracy and 98.13% transmission efficiency estimation precision across the operational spectrum. This paper provides a novel perspective on the QSCR-WPT modeling and paves the way for further exploration of the parameter optimization and control methods of the QSCR-WPT.

Wireless power transfer (WPT) systems have been hamstrung by modest energy efficiencies and electromagnetic safety concerns. Conventional electromagnetic shielding devices can reduce the electromagnetic interference (EMI) to the ambient environment but at the same time deteriorate the transfer performance. In this article, a novel hybrid resonance optimization-based passive shielding magnetic structure and the corresponding circuit are proposed. The shielding structure and topological network have the advantage of minimizing electromagnetic fields (EMFs) around the system while guaranteeing transfer performance (PTE, G_V, P_OUT, phase relation) constant. Moreover, a multiobjective genetic algorithm is utilized to optimize the shielded directional coils (SDCs) parameters in consideration of the transfer efficiency, EMF, and shielding structure volume. Finally, a reasonable prototype of the proposed WPT system is designed, fabricated, and tested. Experimental results show that the maximum leakage EMF level in the evaluated area is reduced by 4.18 dBmV (nearly 39.5 µT). Additionally, the PTE changes by only 1.5%, the G_V changes by just 9.5%, and the phase relationship remains unaffected under the 80 W output power condition. The presented solution merges design approach, compensation network, and optimization plan. It can be further extended to analyze arrays of arbitrary order and shielding in different orientations, providing useful insights for smart homes.

The application of metasurface in wireless power transfer (WPT) system has attracted great attention due to its excellent properties. However, most studies focus on singlefrequency transmission of energy (generally MHz-band frequency), while the operating frequency of most WPT systems is kHz band. In this letter, a cross-frequency (both kHz and MHz bands) metasurface cell for WPT system is designed and equivalent permeability extraction method is proposed for the first time. Firstly, a double-layer nested structure with two different helical coils is utilized to enable the metasurface cell to obtain two different resonant frequencies. Secondly, the equivalent circuit of this metasurface cell is established and detailed theoretical analysis of equivalent relative permeability is derived for cross-frequency metasurface unit cell. Finally, the precise prototype of unit cell is designed. The experimental results agree well with the theoretical ones. This work paves the way to dual-frequency band WPT system based on metasurface. Particularly, it provides a good preparation for the application of cross-frequency metasurface to realize simultaneous wireless power and data transfer in WPT system