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Morel C.,Graduate School of Electronics of the West | Vlad R.,Graduate School of Electronics of the West | Chauveau E.,Technical University of Cluj Napoca
Nonlinear Dynamics | Year: 2010

This paper proposes a method to generate several independent periodic attractors, in continuoustime nonchaotic systems (with an equilibrium point or a limit cycle), based on a switching piecewise-constant controller. We demonstrate here that the state space equidistant repartition of these attractors is on a precise zone of a precise curve that depends on the parameters of the system. We determine the state space domains where the attractors are generated from different initial conditions. A mathematical formula giving their maximal number in function of the controller piecewise-constant values is then deduced. Throughout this study, the proposed methodology is illustrated with several examples. Copyright © 2009 Springer Science+Business Media B.V. Source


Petreus D.,Technical University of Cluj Napoca | Daraban S.,Technical University of Cluj Napoca | Ciocan I.,Technical University of Cluj Napoca | Patarau T.,Technical University of Cluj Napoca | And 2 more authors.
Solar Energy | Year: 2013

This paper presents a novel control and modulation technique applied to a low cost single stage solar micro-inverter. Multiple modulation strategies are analysed and finally an optimal one is proposed and implemented in order to obtain a low total harmonic distortion factor and a power factor close to unity of the current supplied to the grid. The luminosity step time response of the system is improved using two analog control loops: a hysteresis current mode control loop and a voltage loop on the input solar panel voltage. A MPPT power loop is also implemented in order to harvest maximum energy from the solar panel. The simulation times of the entire system is improved by implementing an average model for the inverter. In this way multiple control strategies and MPPT algorithms can be tested and compared in a shorter time. The experimental results validate the theoretical and simulated ones. © 2013 Elsevier Ltd. Source


Daraban S.,Technical University of Cluj Napoca | Petreus D.,Technical University of Cluj Napoca | Morel C.,Graduate School of Electronics of the West
Energy | Year: 2014

This article presents a novel MPPT (maximum power point tracking) algorithm, based on a modified GA (genetic algorithm). When photovoltaic systems are affected by partial shading, a GMPPT (global maximum power point tracking) algorithm is required to increase the energy harvesting capability of the system. A new GMPPT algorithm is proposed in this article: a P&O (perturb and observe) algorithm is integrated inside the GA function and creates a single algorithm. By embedding a simple MPPT algorithm (P&O) inside the structure of the GA, the population size and the number of iterations are decreased, thus finding the MPP (maximum power point) in a shorter time. The algorithm parameters (population size, number of genes, and number of iterations) are optimized and the final solution is provided. A macromodel is used to average the real DC-DC converter and reduce the computation burden of the simulator, thus reducing the simulation time. The control part and the GMPPT algorithm were implemented on a DSP (digital signal processor) and tested on an experimental small scale photovoltaic system. A description of this algorithm and its performances are detailed in this article, verified through simulation and experimental results. © 2014 Elsevier Ltd. Source


Moreau S.,CNRS Acoustic Lab of Du Maine University | Plantier G.,Graduate School of Electronics of the West | Valiere J.-C.,University of Poitiers | Bailliet H.,University of Poitiers | Simon L.,CNRS Acoustic Lab of Du Maine University
Experiments in Fluids | Year: 2011

Spectral estimation of irregularly sampled velocity data issued from Laser Doppler Anemometry measurements is considered in this paper. A new method is proposed based on linear interpolation followed by a deconvolution procedure. In this method, the analytic expression of the autocorrelation function of the interpolated data is expressed as a linear function of the autocorrelation function of the data to be estimated. For the analysis of both simulated and experimental data, the results of the proposed method is compared with the one of the reference methods in LDA: refinement of autocorrelation function of sample-and-hold interpolated signal method given by Nobach et al. (Exp Fluids 24:499-509, 1998), refinement of power spectral density of sample-and-hold interpolated signal method given by Simon and Fitzpatrick (Exp Fluids 37:272-280, 2004) and fuzzy slotting technique with local normalization and weighting algorithm given by Nobach (Exp Fluids 32:337-345, 2002). Based on these results, it is concluded that the performances of the proposed method are better than the one of the other methods, especially for what concerns bias and variance. © 2010 Springer-Verlag. Source


Morel C.,Graduate School of Electronics of the West | Vlad R.,Technical University of Cluj Napoca | Morel J.-Y.,University of Angers | Petreus D.,Technical University of Cluj Napoca
Mathematics and Computers in Simulation | Year: 2011

The present paper introduces a new method to generate several independent periodic attractors, based on a switching piecewise-constant controller. We demonstrate here that the state space equidistant repartition of these attractors is on an arbitrarily precise zone of a paraboloid or plane. We determine the state space domains where the attractors are generated from different initial conditions. A mathematical formula giving their maximal number in function of the controller piecewise-constant values is then deduced. © 2011 IMACS. Source

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