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In the last years the use of the wireless power transfer systems has experienced a significant increase. In this context the study of the behavior of these systems has been the subject of debate for many researchers, in order to understand and improve their performances. This paper aims to bring a contribution in this regard. Based on previous studies, the paper makes a comparative analysis of three...
Recently the information from industry shows that inductive power transfer electric vehicle chargers that use tight coupling between the inductive coupler coils were achieved. This paper includes a theoretical and experimental study on the possibilities that tight coupling offers versus loose coupling - widely used so far - in what concerns the ratio between the output transmitted power and the efficiency...
This paper presents a study of the frequency splitting and bifurcation phenomena in the wireless power transfer systems. Using electric circuit model methods and mathematical calculus, the two phenomena are analyzed for all the possible configurations of the coupled circuits, i.e. seriesseries, series-parallel, parallel-series and parallel-parallel. For a specific case including two identical printed...
The paper proposes to analyze series-series magnetically coupled circuits that include circuits with different natural frequencies. An analytical-numerical calculation on this configuration of coupled circuits was realized. The work was centered on obtaining those frequencies that characterize the extreme points of the load active power — frequency characteristic. The mathematical calculus was correlated...
In this paper we present a sequential computation method of the state vector, for pre-established time intervals or punctually. Based on discrete circuit models with direct or iterative companion diagrams, the proposed method is intended to a wide range of analog dynamic circuits: linear or nonlinear circuits with or without excess elements or magnetically coupled inductors. Feasibility, accessibility...
Recent approaches for time-domain analysis of lumped circuits deal with differential-algebraic-equation (DAE) systems instead of SPICE-type resistive models. Although simple and powerful, DAE models based on modified nodal approaches require some restrictions related to redundant variables or circuit topology. In this context, the paper proposes an improved version that allows treating nonlinear analog...
The paper is focused on the exact analysis of the frequency splitting and bifurcation phenomena in the wireless power transfer (WPT) systems with series-parallel, parallel-series and parallel-parallel resonators. Starting from the analysis in sinusoidal behavior of a WPT system we build, using the algebraic equation theory, the exact splitting mathematical model for any connection of the WPT systems...
The paper treats the wireless power transfer systems with series-series resonators from the point of view of the frequency splitting and bifurcation phenomena. We develop an exact mathematical model of the splitting phenomena (splitting equation) based on the algebraic equation theory, which allows finding exact values of the splitting frequencies. This is extremely useful to setup the magnetic coupling...
This paper proposes to analyze the influence of the displacement of the capacitor plates on the performances of an electrical coupled contactless power transfer system. The armatures are of circular form and the values of their radii are different. Some formulae are obtained and based on them graphical representations are made in order to analyze the nonlinear behavior. Then these variable values...
Voltage controlled microwave oscillators are used in digital communication systems. Pairs of coupled and synchronized voltage controlled oscillators are used to control the phase in microwave antenna arrays as an alternative to other methods. A particular phase shift can be obtained by choosing the free-running frequencies of the oscillators in the array. The aim of this paper is to analyze such a...
Two procedures for parameter estimation for linear analog circuits are presented and verified on a pair of magnetic coupled resonators used in wireless power transfer applications. The parameters of interest are those which are difficult or impossible to be measured directly. Starting from the equivalent diagram of the analog circuit in sinusoidal behavior, we build the mathematical model based on...
In the paper, the 2-D finite element method implemented with FLUX software was employed to finding the optimal airgap of smoothing inductors with resistive load. The optimal design of nonlinear saturable inductors depends on the power converter characteristics and on the load. The optimal airgap is usually a standard value according to catalog data. The working conditions of the smoothing inductor...
This paper presents a method to assess the losses in electromagnetic devices starting from accurately measured values of the voltages and of the currents, for many levels of supply voltages, including those that produce a strong saturation of the ferromagnetic core. The method was implemented in a MATLAB program that allows computing the total losses, but also their components (i.e. eddy current losses...
In this paper, a method for the identification and separation of the ferrous and non ferrous metal waste, as well as of their alloys, is described. For this purpose, the obtained results using an experimental device based on eddy currents are presented. One probe coil having an open magnetic circuit made from Mn Zn ferrite, U type is supplied with a high frequency sinusoidal AC voltage. The probe...
The paper is focused on a useful application related to our optimization technique of the arrays of coupled oscillators at millimeter-wave frequencies, a pair of voltage-controlled oscillators coupled through a two-port passive network being treated. A distinct section of the paper is focused on a method to estimate unknown circuit parameters starting from measurements performed on the real system,...
The metallic waste management, from industrial or household activities, is of great actuality. In this context, the sorting of the mixtures of metallic materials and the identification of the non-ferrous and ferrous metallic pieces is of high interest for operators in the field. This paper presents the results achieved using our experimental device based on eddy currents for ferrous and non-ferrous...
The paper is a general survey on power transfer by induction. The physical principle is pointed out and the constraints for an optimal operation applied both to the emitter and receiver are specified. Couple mode theory is used to study the wireless power transfer and a comparison with the circuit theory results is made. The analysis is focused on the power transfer efficiency in connection with the...
Our paper presents a new method to estimate the analog circuit parameters based on some measurements performed on the real circuit, the parameters of interest being those which are difficult or impossible to be measured directly. Starting from the equivalent scheme of an analog circuit in sinusoidal behavior, we generate the network function in full symbolic form, obtaining an appropriate frequency...
The paper presents an improvement of sensitivity and tolerance analysis method for the Voltage-Controlled Oscillator (VCO) circuits with Van der Pol model. The tolerance analysis method is based on the Monte Carlo Analysis (MCA) and on the Fast Monte Carlo Analysis (FMCA) based on the circuit transfer function. The circuit sensitivities are computed by means of the derivatives of the circuit transfer...
The paper proposes effective solutions to include nonlinear inductors with soft ferromagnetic core in the time-domain circuit analyses. Three inductor models are developed, tested and compared. They are conceived for different degrees of accuracy related to the real devices. The models are robust and reliable due to the modeling concept that avoids numerical instabilities. An enhanced inductor model...
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