Inductive power transfer (IPT) and Capacitive power transfer (CPT) are mainly two effective ways to achieve wireless power transfer (WPT). IPT system needs capacitor to compensate the system, while the CPT system requires inductor to tune the system. Therefore, IPT coupler can be used to compensate the CPT coupler and vice versa. In this paper, an Inductive and capacitive hybrid wireless power transfer (HWPT) system is proposed to improve the system coupler anti-misalignment ability. The couplers of IPT and CPT are employed together to compensate each other and transfer power together. Superposition theory is used to analyze the system working principle in detail. With the analysis results, a scaled-down system is built to validate the performance of the proposed approach. Experimental results show that the proposed HWPT system can achieve 653 W output power with 87.7% DC-DC efficiency at the well-aligned condition, and the maximum variation of output power is 8.3% with the coupler misalignment from 0 to 270 mm(half-width of the coupler), which agree well with analysis results.

This study proposed a hybrid inductive and capacitive wireless power transfer system to achieve high‐power transfer by combining inductive power transfer (IPT) and capacitive power transfer (CPT). A traditional IPT system imposes a high voltage on the transmitter because of resonance. Meanwhile, high voltages are required to establish an electric field to deliver power to the CPT system. Therefore, they can be combined to a hybrid system to achieve high‐power transfer by utilising two power transfer paths. A general model of the hybrid IPT and CPT coupler is analysed in detail. With a series–series compensation topology, 1.1 kW hybrid system with equal power transferred by two paths is simulated and set up to evaluate the performance of the proposed method. An experimental prototype is built under various conditions, and the result shows that the hybrid system achieved 1.1 kW output power through both of magnetic path and of electric path successfully with 91.9% DC–DC efficiency.

It is well known that a high voltage across the coupling plates of a Capacitive Power Transfer (CPT) system is beneficial to increase its power transfer capability, but a high voltage may lead to high insulation requirements and cause safety concerns. This paper proposes a compensation design method for achieving the maximum power of CPT systems under coupling voltage constraints. Basic on a simplified capacitive coupling model and thorough power transfer characteristics analysis, a family of compensation topologies are derived to maintain a 90 degrees phase shift between the input and output voltages across the CPT coupler against load variations, so that the coupling voltages (which practically need to be limited) are fully utilized for power transfer purposes. A full design process for determining the compensation parameters is presented, and an example 2kW CPT system is built and tested using LC compensation at the primary side to boost the input voltage to the coupler; and one of the proposed compensation topologies (CLC) at the secondary side for impedance transformation of a given load with a specified voltage and power requirements. Experimental results show a good agreement with theoretical analysis, which demonstrate the phase difference between the voltages before and after the coupler is kept nearly 90 degrees, and a maximum possible power transfer of 2.039kW is achieved under the given voltage limits and coupling conditions. A system end to end (DC-DC) efficiency of 90.29% is obtained when the air gap between the coupling plates is 150mm, and the coupling capacitance is only 13.84 pF.

Capacitive power transfer (CPT) uses an electric field as the transfer medium to achieve wireless power transfer (WPT). Benefitting from the low eddy current loss, simple system structure and strong plasticity of the coupling coupler, the CPT system has recently gained much attention. The CPT system has significantly improved transfer power, system efficiency, and transfer distance due to continuous research and discussion worldwide. This review briefly presents the basic working principle of the CPT system and summarizes the theoretical research in four aspects, including coupling coupler and high-frequency power converter. Following this, the review focuses on research in six key directions, including system modelling and efficiency optimization. The application of CPT technology in five fields, including medical devices and transportation, is also discussed. This review introduces the progress of CPT research in recent years, hoping to serve as a reference for researchers, to promote the further research and application of the CPT system.

Conventionally, the magnetic core in an inductive power transfer (IPT) system is spliced by pieces of ferrites, which is time-consuming and unable to realize a seamless fit on the curved surface. This letter proposes a compact curved coupler with a novel flexible nanocrystalline flake ribbon (NFR) magnetic core. Compared with ferrite core, the NFR not only enhances the application flexibility of the IPT system but also significantly reduces its weight in certain power. Based on the LCC -S compensation topology, a 1 kW IPT prototype for autonomous underwater vehicles is fabricated. The transmission characteristics and temperature performance of the system have been investigated under three power levels, considering various permeability values for NFR cores. Finally, the NFR with a permeability of 800 is chosen as the magnetic core, and the dc–dc system efficiency reaches 92.85%. Moreover, it is possible to restrict the maximum temperature to 54.1 °C, and the weight of the NFR cores accounts for merely 4.65% of the whole coupler.

A general mutual coupling model of multiple input and/or multiple output (MIMO) capacitive coupling interface with an arbitrary number of ports is proposed. In the model proposed in this letter, all the capacitances between the metal plates are taken into account. The self-capacitance of each port and mutual capacitances between the two ports are defined, and a simple equivalent circuit composed of self capacitances and current-controlled voltage sources is obtained. The proposed model helps to reduce the complexity of the MIMO capacitive coupling interface and can be used to simplify the analysis of the power transfer performance of MIMO capacitive power transfer systems. An example capacitive coupling interface setup with two input ports and two output ports is built and tested. The measured and model-based theoretical results of the self and mutual capacitances of the capacitive coupling interface are compared and found to be in good consistency, which verifies the correctness of the proposed model.