Efficient wireless non-radiative mid-range energy transfer
TL;DR: In this article, the physical phenomenon of long-lifetime resonant electromagnetic states with localized slowly-evanescent field patterns was investigated to transfer energy efficiently over non-negligible distances even in the presence of extraneous environmental objects.
About: This article is published in Annals of Physics.The article was published on 2008-01-01 and is currently open access. It has received 1628 citations till now. The article focuses on the topics: Radiative transfer.
Citations
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TL;DR: A quantitative model is presented describing the power transfer of self-resonant coils in a strongly coupled regime, which matches the experimental results to within 5%.
Abstract: Using self-resonant coils in a strongly coupled regime, we experimentally demonstrated efficient nonradiative power transfer over distances up to 8 times the radius of the coils We were able to transfer 60 watts with ∼40% efficiency over distances in excess of 2 meters We present a quantitative model describing the power transfer, which matches the experimental results to within 5% We discuss the practical applicability of this system and suggest directions for further study
5,284 citations
TL;DR: A circuit model is presented along with a derivation of key system concepts, such as frequency splitting, the maximum operating distance (critical coupling), and the behavior of the system as it becomes undercoupled, including the introduction of key figures of merit.
Abstract: Wireless power technology offers the promise of cutting the last cord, allowing users to seamlessly recharge mobile devices as easily as data are transmitted through the air. Initial work on the use of magnetically coupled resonators for this purpose has shown promising results. We present new analysis that yields critical insight into the design of practical systems, including the introduction of key figures of merit that can be used to compare systems with vastly different geometries and operating conditions. A circuit model is presented along with a derivation of key system concepts, such as frequency splitting, the maximum operating distance (critical coupling), and the behavior of the system as it becomes undercoupled. This theoretical model is validated against measured data and shows an excellent average coefficient of determination of 0.9875. An adaptive frequency tuning technique is demonstrated, which compensates for efficiency variations encountered when the transmitter-to-receiver distance and/or orientation are varied. The method demonstrated in this paper allows a fixed-load receiver to be moved to nearly any position and/or orientation within the range of the transmitter and still achieve a near-constant efficiency of over 70% for a range of 0-70 cm.
1,630 citations
Cites background from "Efficient wireless non-radiative mi..."
...used for wireless power transfer [7]–[13] have shown the potential to deliver power with more efficiency than far-field approaches, and at longer ranges than traditional inductively...
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TL;DR: The aim is to provide a contemporary look at the current state of the art in IWSNs and discuss the still-open research issues in this field and to make the decision-making process more effective and direct.
Abstract: In today's competitive industry marketplace, the companies face growing demands to improve process efficiencies, comply with environmental regulations, and meet corporate financial objectives. Given the increasing age of many industrial systems and the dynamic industrial manufacturing market, intelligent and low-cost industrial automation systems are required to improve the productivity and efficiency of such systems. The collaborative nature of industrial wireless sensor networks (IWSNs) brings several advantages over traditional wired industrial monitoring and control systems, including self-organization, rapid deployment, flexibility, and inherent intelligent-processing capability. In this regard, IWSN plays a vital role in creating a highly reliable and self-healing industrial system that rapidly responds to real-time events with appropriate actions. In this paper, first, technical challenges and design principles are introduced in terms of hardware development, system architectures and protocols, and software development. Specifically, radio technologies, energy-harvesting techniques, and cross-layer design for IWSNs have been discussed. In addition, IWSN standards are presented for the system owners, who plan to utilize new IWSN technologies for industrial automation applications. In this paper, our aim is to provide a contemporary look at the current state of the art in IWSNs and discuss the still-open research issues in this field and, hence, to make the decision-making process more effective and direct.
1,595 citations
Cites methods from "Efficient wireless non-radiative mi..."
...using magnetic coupling between two copper coils is possible [13]....
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TL;DR: This work has analyzed the four-coil energy transfer systems and outlined the effect of design parameters on power-transfer efficiency, and a proof-of-concept prototype system is implemented and confirms the validity of the proposed analysis and design techniques.
Abstract: Resonance-based wireless power delivery is an efficient technique to transfer power over a relatively long distance. This technique typically uses four coils as opposed to two coils used in conventional inductive links. In the four-coil system, the adverse effects of a low coupling coefficient between primary and secondary coils are compensated by using high-quality (Q) factor coils, and the efficiency of the system is improved. Unlike its two-coil counterpart, the efficiency profile of the power transfer is not a monotonically decreasing function of the operating distance and is less sensitive to changes in the distance between the primary and secondary coils. A four-coil energy transfer system can be optimized to provide maximum efficiency at a given operating distance. We have analyzed the four-coil energy transfer systems and outlined the effect of design parameters on power-transfer efficiency. Design steps to obtain the efficient power-transfer system are presented and a design example is provided. A proof-of-concept prototype system is implemented and confirms the validity of the proposed analysis and design techniques. In the prototype system, for a power-link frequency of 700 kHz and a coil distance range of 10 to 20 mm, using a 22-mm diameter implantable coil resonance-based system shows a power-transfer efficiency of more than 80% with an enhanced operating range compared to ~40% efficiency achieved by a conventional two-coil system.
894 citations
Cites methods from "Efficient wireless non-radiative mi..."
...Coupled-mode theory [18] has been used to explain this phenomenon in [19]–[21]....
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...2) Four-Coil System: Couple-mode theory [18] has been originally used to describe resonance-based coupling [19], [20]....
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References
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Book•
01 Jan 1982
TL;DR: The most up-to-date resource available on antenna theory and design as mentioned in this paper provides an extended coverage of ABET design procedures and equations making meeting ABET requirements easy and preparing readers for authentic situations in industry.
Abstract: The most-up-to-date resource available on antenna theory and design Expanded coverage of design procedures and equations makes meeting ABET design requirements easy and prepares readers for authentic situations in industry New coverage of microstrip antennas exposes readers to information vital to a wide variety of practical applicationsComputer programs at end of each chapter and the accompanying disk assist in problem solving, design projects and data plotting-- Includes updated material on moment methods, radar cross section, mutual impedances, aperture and horn antennas, and antenna measurements-- Outstanding 3-dimensional illustrations help readers visualize the entire antenna radiation pattern
14,065 citations
01 Jul 1984
5,335 citations
Journal Article•
TL;DR: A brief history of microwave engineering is given in this paper, where the impact of computer-aided design and monolithic microwave integrated circuits on microwave design is examined, along with suggestions for related studies that would be useful to the microwave engineer.
Abstract: A brief history of microwave engineering is given. The impact of computer-aided design and monolithic microwave integrated circuits on microwave design is examined. The career potential of microwave engineering is discussed, along with suggestions for related studies that would be useful to the microwave engineer. >
3,169 citations