Development Of Wireless Power Transfer Research Articles

Scheduling Precedence Constraints among Charging Tasks in Wireless Rechargeable Sensor Networks

The development of wireless power transfer (WPT) facilitates wireless rechargeable sensor networks (WRSNs) receiving considerable attention in the sensor network research community. Most existing works mainly focus on general charging patterns and metrics while overlooking the precedence constraints among tasks, resulting in charging inefficiency. In this paper, we are the first to advance the issue of scheduling wireless charging tasks with precedence constraints (SCPC), with the optimization objective of minimizing the completion time of all the charging tasks under the precedence constraints while guaranteeing that the energy capacity of the mobile charger (MC) is not exhausted and the deadlines of charging tasks are not exceeded. In order to address this problem, we first propose a priority-based topological sort scheme to derive a unique feasible sequence on a directed acyclic graph (DAG). Then, we combine the proposed priority-based topological sort scheme with the procedure of a genetic algorithm to obtain the final solution through a series of genetic operators. Finally, we conduct extensive simulations to validate our proposed algorithm under the condition of three different network sizes. The results show that our proposed algorithm outperformed the other comparison algorithms by up to 11.59% in terms of completion time.

Design of a Strong Robust Wireless Power Transfer System With Wide-Range Output Regulation Based on Dual-Band Architecture

With the continuous development of wireless power transfer (WPT) equipment in the direction of miniaturization, how to adapt the traditional sensitive Class E system to high-voltage, high-power and wide-range adjustable output occasions has become a crucial research issue. Here, compared with the other two, the difficulty of improving the system robustness under the large power fluctuation and achieving the system's wide-range output voltage regulation is much greatly. Aiming at the above difficulties, a novel dual-band system architecture based on power synthesis is proposed, the power variation of the megahertz (MHz) WPT subsystem is actively compressed by the kilohertz (kHz) WPT subsystem with strong robustness and the high-frequency subsystem only needs to bear relatively low power fluctuations, thereby reducing the difficulty of system design and ensuring the efficient operation. Meanwhile, compared with the traditional system, the Buck circuit only needs to perform partial power regulation to achieve the wide range of voltage output. To verify the feasibility of the proposed architecture, a 200W experimental prototype was built, with a maximum efficiency of 89%.

Principles and applications of wireless energy transmission

In this day and age, people's lives are inextricably linked to electricity, which is being used more and more in everyday life. The traditional transmission of electrical energy usually uses materials such as metal wires and cables as the transmission medium, and the losses and potential damage (line deterioration, tip discharges) caused by this transmission medium are inevitable. The introduction of radio has been very effective in reducing this situation, and the development of Wireless Power Transfer (WPT) technology has seen three major developments since then, with Tesla lighting a phosphorescent lamp at the Colombian World's Fair in 1893, igniting hopes for WPT. This new way of transmitting electrical energy has expanded the imagination of people in terms of power supply methods by making it possible to provide more freedom in situations where cable charging is not suitable.The working theory, fundamental design, and potential applications of wireless energy transmission technology are covered in this study. By doing this, it offers insight into the development and use of wireless energy transmission technology as it is now. In the end, it is envisaged that the market will adopt wireless energy transfer technology extensively.

Deep learning for online computation offloading and resource allocation in NOMA

The limited battery capacity and low computing capability of wireless Internet of Things (IoT) devices can hardly support computation-intensive and delay-sensitive applications. While recent development of wireless power transfer (WPT) and mobile edge computing (MEC) technologies help IoT devices harvest energy and offload computation tasks to edge servers. While it is still challenging to design an efficient offloading policy to improve the performance of the IoT network. In this article, we consider a MEC network that has WPT capability and adopts the non-orthogonal multiple access (NOMA) technology to offload tasks partially. Our goal is to propose an online algorithm to optimize resource allocation under a wireless dynamic channel scenario. In order to obtain the optimal offloading decision and resource allocation efficiently, we propose a Deep Reinforcement learning-based Online Sample-improving (DROS) framework which implements a deep neural network to input the discretized channel gains to obtain the optimal WPT duration. Based on the WPT duration derived by DNN, we design an optimization algorithm to derive the optimal energy proportion for offloading data. Numerical results verify that compared with traditional optimization algorithms, our proposed DROS has significantly sped up convergence for better solutions.

Constant-Current and Constant-Voltage Output for Single-Switch WPT System with Composite Shielding Structure

With the development of wireless power transfer (WPT), the wireless charging has become a research hotspot. This paper proposes a novel single-switch hybrid compensation topology, which can change the compensation network to realize the constant-current (CC) and constant-voltage (CV) output. The zero voltage switching (ZVS) margin can be designed to increase the stability of the system. In addition, the magnetic coupler adopts a composite shielding structure composed of ferrite, nanocrystalline, and aluminium foil. The composite shielding structure has a better shielding effect on magnetic flux leakage, and its weight is lighter. The composite shielding structure is expected to be used in the wireless charging system of electric vehicles (EVs). Finally, an experimental prototype is built to verify the theoretical analysis, and the maximum efficiency can reach 91.4%.

Design of High-Power Static Wireless Power Transfer via Magnetic Induction: An Overview

Recent years have witnessed the booming development of wireless power transfer (WPT) via magnetic induction, which has the advantages of convenience, safety, and feasibility to special occasions. WPT can be applied to electric vehicles and ships, where high-power WPT technology is required to shorten the charging time with the increasing battery capacity. This paper reviews the state-of-the-art development of high-power static WPT systems via magnetic induction. Selected prototypes and demos of high-power WPT systems are demonstrated with key transfer characteristics and solutions. Theoretical foundation of magnetically coupled WPT systems is analyzed and the maximum power capability of coils is derived. Compensation topologies suitable for high-power applications are discussed. Four basic planar coils, namely the bipolar coil, the square coil, the circular coil, and the rectangular coil, are simulated and compared. The state-of-the-art silicon carbide MOSFET development is introduced. The power electronics converters with power elevation techniques, including cascading, paralleling and inductive elevation, are investigated. Future development of high-power WPT systems is discussed.

A Multireceiver Wireless Power Supply System with Power Equalization in Stereoscopic Space

With the rapid development of wireless power transfer (WPT) technology, the traditional single-transceiver WPT system has become more and more advanced; however, it is still difficult to meet its extensive application requirements. Aiming at the wireless charging of mobile phones in public places, electric vehicles (EVs) in multistorey garages, and electronic shelf labels (ESLs) in supermarket merchandise shelves, a multireceiver wireless power supply system with power equalization is proposed. The condition of power equalization is derived according to the equivalent circuit of the proposed WPT system, and the received power can be equally maintained by adjusting the transceiver loop resistance when the total load number or transmission distance changes. A simulation model is established to evaluate the electromagnetic environment of the proposed WPT system, and the results comply with the electromagnetic safety of the ICNIRP-2018 guidelines. Finally, the experimental results show that the power differential rate that meets the power equalization condition is 13 to 17% lower than that of the unsatisfied rate, which verifies the effectiveness of the proposed system in terms of power equalization.

Low-Frequency Medium Power Capacitor-Free Self-Resonant Wireless Power Transfer

With the rapid development of wireless power transfer (WPT), the self-resonant WPT system without using additional compensation capacitors has attracted attention. However, most of reported self-resonant WPT systems have low power transfer (less than 100 W) and high operating frequencies at megahertz. In this article, four multilayer, self-resonant WPT coil pads with different dielectrics are designed and experimentally validated. The aim of this article is to increase the power rating and decrease the operating frequency for capacitor-free WPT system compared to reported systems used in consumer electronics. Analysis of integrated compensation capacitance, inductance, and parasitic capacitance of the coil is provided. Finite-element analysis is used to evaluate four dielectric materials, mica, polypropylene, polyimide, and fiberglass. An experimental setup has been developed, which can achieve more than 360-W power transfer for a 120 mm air gap with an efficiency of 82% and an operating frequency of near 80 kHz.

TLFW: A Three-Layer Framework in Wireless Rechargeable Sensor Network with a Mobile Base Station

Wireless sensor networks as the base support for the Internet of things have been a large number of popularity and application. Such as intelligent agriculture, we have to use the sensor network to obtain the growing environment data of crops and others. However, the difficulty of power supply of wireless nodes has seriously hindered the application and development of Internet of things. In order to solve this problem, people use low-power sleep scheduling and other energy-saving methods on the nodes. Although these methods can prolong the working time of nodes, they will eventually become invalid because of the exhaustion of energy. The use of solar energy, wind energy, and wireless signals in the environment to obtain energy is another way to solve the energy problem of nodes. However, these methods are affected by weather, environment, and other factors, and they are unstable. Thus, the discontinuity work of the node is caused. In recent years, the development of wireless power transfer (WPT) has brought another solution to this problem. In this paper, a three-layer framework is proposed for mobile station data collection in rechargeable wireless sensor networks to keep the node running forever, named TLFW which includes the sensor layer, cluster head layer, and mobile station layer. And the framework can minimize the total energy consumption of the system. The simulation results show that the scheme can reduce the energy consumption of the entire system, compared with a Mobile Station in a Rechargeable Sensor Network (MSiRSN).

Multi-mode metamaterial-inspired resonator for near-field wireless power transfer

The modern development of wireless power transfer (WPT) technologies brings various products that improve the lives of users. It has become an urgent demand to simultaneously charge multiple mobile devices operating under different WPT standards on a charging platform regardless of their position and orientation with respect to each other. Recent advances in metasurfaces make it possible to control the near electromagnetic fields with much more degrees of freedom in comparison to conventional resonators. Here, we develop a compact multi-mode metamaterial-inspired resonator formed as an array of sub-wavelength parallel strip conductors. This resonator aims to replace conventional flat coil resonators and offers multiple modes with different profiles of electromagnetic field distribution for various near-field WPT applications. The first three eigenmodes are numerically and experimentally studied, and their potential applications for design of multi-mode WPT systems capable of charging multiple receivers simultaneously are discussed.

On the Load-Independence of a Multi-Receiver Wireless Power Transfer System

Research and development of wireless power transfer (WPT) systems has attracted much attention in recent years for their potential widespread applications. One of the much desirable features of a WPT system is load-independence. In this letter, we propose the insertion of a simple T-type network into a multi-receiver WPT magnetically coupled resonant WPT system to achieve the load-independence. We then present theoretical analysis, simulation, and experimental verifications; as a result, they lay the foundation for further investigations, improvements, and implementations of realistic WPT systems.

Radio Inference Analysis for WPT Embedded Digital Living Things in Coexistence with NFC Devices in Smart Home Microgrid Facility

The rapid development of wireless power transfer (WPT) in mobile devices and Internet of Things (IoT) Technologies inspires the research interest to support the wireless power charging capability on digital living equipment to manage energy sources effectively. As energy consumption in our day to day life is steadily increases the demand, the trend for energy harvesting technology also grows and there is an increasing number of an independent IoT based microgrid facility is built using solar panels in smart home. The digital living things are usually placed in a narrow space with microgrid facility. However, The IoT connected digital living is placed independently in a large space. The WPT will give interference to electrical equipments and electric utility meter in microgrid facility. This paper is focused on analyzing the coexistence between WPT and electric utility meter in an IoT based smart home microgrid facility. The separation distance between WPT and electric utility meter and the allowable numbers of WPT are suggested in order to protect electric utility meter from interference of WPT on the basis of interference scenario. The Monte Carlo method is used for the impact analysis of WPT supporting digital living things on energy utility meter built-in with Near Field Communication.

Review and research progress of wireless power transfer for railway transportation

This paper discusses the history and research progress of wireless power transfer (WPT) for railway transportation. In the field of railway transportation traction power supply, the problems caused by the traditional contact‐type power supply method have become increasingly prominent: the overhead contact network prone to breakages, scraping and wearing the pantograph, etc. WPT technology, which avoids direct contact with the power supply sources and loads, effectively solves these problems. This paper focuses on the application of WPT technology for railway transit, and introduces the research status in China and abroad. Moreover, the main technologies and primary problems of WPT, including magnetic coupler, segmented power supply, design of high‐frequency inverter, system optimization and control and practical applications for trams, maglev vehicles, and high‐speed trains, are reviewed. A detailed analysis and summary on the technologies is also provided. By reviewing the state‐of‐the‐art development of WPT in railways, it is hoped that researchers could be encouraged by these achievements and pushed forward the further development in WPT. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Joint Power Waveforming and Beamforming for Wireless Power Transfer

In the Internet of Things, wireless devices need more easily accessible energy resources, which motivates the development of wireless power transfer (WPT) using radio frequency signals. Beamforming technique has been widely adopted by using multiple transmit antennas to form a sharp energy beam toward an intended receiver. However, few of them have considered the potential gain of multipath propagation. In this paper, we propose a joint power waveforming and beamforming in the time domain for WPT, in which the waveforms on multiple transmit antennas driven by a common reference signal are designed to maximize the gain of energy delivery efficiency. We consider both nonperiodic and periodic reference signals and propose low-complexity waveforms that can achieve near-optimal performance. It is found that the energy delivery efficiency gain of the proposed approach increases with the waveform length until saturation. We theoretically analyze the outage probability of the proposed approach under a uniform power delay channel profile, which quantifies the impact of the number of antennas and multipaths. Simulations are performed to validate the theoretic analysis and the effectiveness of the proposed joint power waveforming and beamforming approach.

Joint Power Charging and Routing in Wireless Rechargeable Sensor Networks.

The development of wireless power transfer (WPT) technology has inspired the transition from traditional battery-based wireless sensor networks (WSNs) towards wireless rechargeable sensor networks (WRSNs). While extensive efforts have been made to improve charging efficiency, little has been done for routing optimization. In this work, we present a joint optimization model to maximize both charging efficiency and routing structure. By analyzing the structure of the optimization model, we first decompose the problem and propose a heuristic algorithm to find the optimal charging efficiency for the predefined routing tree. Furthermore, by coding the many-to-one communication topology as an individual, we further propose to apply a genetic algorithm (GA) for the joint optimization of both routing and charging. The genetic operations, including tree-based recombination and mutation, are proposed to obtain a fast convergence. Our simulation results show that the heuristic algorithm reduces the number of resident locations and the total moving distance. We also show that our proposed algorithm achieves a higher charging efficiency compared with existing algorithms.

Coupled optic-thermodynamic analysis of a novel wireless power transfer system using concentrated sunlight for space applications

The energy generation and supply for in-orbit spacecraft have become an urgent problem concerning efficient and economical utilization of spacecraft formation flying. To fill the gap between the requirement of inter-spacecraft energy transfer and the development of wireless power transfer, this paper presents a novel wireless power transfer system whose transmission medium is concentrated sunlight. The system concentrates sunlight using a Fresnel lens, and changes the direction of concentrated sunlight beam with optical fibers. The light energy is converted to thermal form by a heat collector, and then it is utilized to generate electricity by a Stirling engine integrated with linear alternator. Equipments employed on fractionated spacecraft shall be supported by this electric energy. A coupled optic-thermodynamic model was developed to analyze system link efficiencies. This system offers characteristics such as high flexibility, relatively low cost for launch and maintenance, and most importantly, high end-to-end efficiency. Simulation results show that the geometric concentration ratio and the temperature ratio of expansion and compression spaces are two key parameters of this system. Output power of 234.3W was achieved on the distance of 100m, and the end-to-end efficiency of the system was above 20%.

Development of Wireless Power Transfer using Capacitive Method for Mouse Charging Application

Wireless power transfer (WPT) is a non-contact power transfer within a distance. With the advantage of not-contact concept, WPT enhances the flexibility movement of the devices. Basically, there are three types of the WPT which are inductive power transfer (IPT), Capacitive Power Transfer (CPT) and Acoustic Power Transfer (APT). Among these, capacitive power transfer (CPT) has the advantages of confining electric field between coupled plates, metal penetration ability and also the simplicity in circuit topologies. Therefore, we focus on the capacitive method in this paper. To be specific, this paper aims to develop a wireless mouse charging system using capacitive based method. This method enables wireless power transmission from mouse pad to a wireless mouse. Hence, no battery requires to power up the mouse. In this paper, a high efficiency Class-E converter is described in details to convert the DC source to AC and the compensation circuit of resonant tank is also proposed at the transmitter side in order to improve the efficiency. In the end, a prototype is developed to prove the developed method. The performances analysis of the developed prototype is discussed and the future recommendation of this technique is also presented.

Wireless Power Transfer for Electric Vehicle Applications

Wireless power transfer (WPT) using magnetic resonance is the technology which could set human free from the annoying wires. In fact, the WPT adopts the same basic theory which has already been developed for at least 30 years with the term inductive power transfer. WPT technology is developing rapidly in recent years. At kilowatts power level, the transfer distance increases from several millimeters to several hundred millimeters with a grid to load efficiency above 90%. The advances make the WPT very attractive to the electric vehicle (EV) charging applications in both stationary and dynamic charging scenarios. This paper reviewed the technologies in the WPT area applicable to EV wireless charging. By introducing WPT in EVs, the obstacles of charging time, range, and cost can be easily mitigated. Battery technology is no longer relevant in the mass market penetration of EVs. It is hoped that researchers could be encouraged by the state-of-the-art achievements, and push forward the further development of WPT as well as the expansion of EV.