1,720,995 research outputs found
Gains Maximization for Two-port WPT Links with Three Coils
No full textIn this paper a two-port network for wireless power transfer realized with three coils is considered. Usually, these networks are analyzed assuming that one of the three mutual couplings is negligible. However, this hypothesis is not always applicable, there are specific configurations for which no coupling can be neglected. Accordingly, in this paper the optimal terminating impedances are derived for the general case where all the couplings are taken into account. The performance of the network are described by using the three power gains (available, power, transducer gains). Analytical formulas and circuital simulations are reported and discussed
On the Use of Matching Networks and Relays for Maximizing the Gains of IR WPT Links
No full textThis paper analyzes the problem of maximizing the gains of a single transmitter-single receiver inductive resonant Wireless Power Transfer link (WPT). Two different approaches are considered and compared: the use of impedance matching networks and the use of additional resonators (relay elements). It is shown that, if from a theoretical point of view the two approaches are equivalent, in some practical cases the maximization of the gains by means of relays may not be feasible
Maxwell's Equations and Potentials in Dirac form using Geometric Algebra
No full textThe basis for engineering electromagnetic computations still relies on Gibbs' vector algebra. It is well known that Clifford algebra (geometric algebra) presents several enhancement on the latter. In this paper it is shown that Maxwell's equations can be cast in a form similar to Dirac equation by using spinors. Additionally, a similar relation is derived for the fields and the potentials. It is also shown that, as a consequence of using the geometric algebra approach, the Lorenz gauge comes naturally from the grade structure
Fast and robust inexact Newton approach to the harmonic-balance analysis of nonlinear microwave circuits
No full textThe letter discusses a novel approach to nonlinear microwave circuit simulation by the harmonic-balance (HB) technique. The nonlinear system is solved by an inexact Newton method, and the GMRES iteration is used at each step to find a suitable inexact Newton update. The peculiar structure of the Jacobian matrix allows the basis vectors of the Krylov subspace to be computed mostly by the FFT. The resulting simulation tool is fast and robust, and outperforms conventional HB techniques when applied to large-size nonlinear analysis problems
Load-Independent Operative Regime for an Inductive Resonant WPT Link in Parallel Configuration
No full textIn this article, the possibility of obtaining a load-independent regime for a wireless power transfer link consisting of two magnetically coupled resonators in parallel configuration is discussed. Analytical formulas and experimental data to achieve a load-independent output voltage or current are presented. With regard to the input side, the cases of a current and a voltage generator are considered. It is shown that when the source is a current generator, either a constant output voltage or a current can be achieved by suitably choosing the operating frequency. As per the case of a voltage generator, by acting on the operating frequency, only a constant output current can be obtained
Load-independent inductive resonant WPT links
No full textThis paper presents the conditions and the design equations for obtaining a load-independent regime for an inductive resonant wireless power transfer link implemented through parallel resonators. The cases of a current and a voltage generator are analyzed and the possibility of obtaining a constant output voltage/current by operating at a suitable frequency is discussed. It is shown that in the case of a voltage generator it is not possible to choose the operating frequency so to obtain a constant output voltage, while it is possible to obtain a constant output current. Conversely, in the case of a current source, a load-independent output in terms of either voltage or current can be obtained by properly selecting the operating frequency
Gains maximization via impedance matching networks for wireless power transfer
No full textWireless Power Transfer (WPT) based on resonant magnetic coupling is an attractive technology for enabling the wireless recharge of electric devices and systems. One of the main drawbacks of this technology is related to the dependence of the efficiency and the power delivered to the load on possible variations of the coupling coefficient and load impedance. In order to alleviate the effects of this dependence, the optimization of appropriate adaptive matching networks is proposed in this paper. The three power gains usually adopted in the context of two-port active networks are assumed as figures of merit in the optimization process. It is theoretically and experimentally demonstrated that the maximum realizable gain of the link is achieved when the conjugate image impedance matching is realized by appropriate matching networks at both the input and output ports of the WPT link
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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