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Zengin S.,Ege University | Deveci F.,Ege University | Deveci F.,Electronic Control Systems | Boztepe M.,Ege University
IEEE Transactions on Power Electronics | Year: 2013

Electrolytic capacitors as a decoupling reservoir restrict the lifetime of photovoltaic (PV) microinverters. This has led to the development of several improved decoupling circuits that can reduce the capacitor value to allow the use of nonelectrolytic types. In this paper, the minimum decoupling capacitor value for the proper operation of discontinuous conduction mode flyback PV microinverters is analyzed by taking into account the total harmonic distortion (THD) and PV power utilization ratio. The results presented show that the decoupling capacitor value influences the THD more than PV power utilization. A decoupling capacitor selection method for single-stage and two-stage flyback inverters is proposed. Experimental results obtained on an 80-W test bench are presented. © 1986-2012 IEEE.

Zengin S.,Ege University | Deveci F.,Electronic Control Systems | Boztepe M.,Ege University
IET Power Electronics | Year: 2013

Flyback-type micro-inverter is an attractive solution for photovoltaic ac-module applications because of several advantages; such as simple current control, working without ac current sensor and potentially low cost. However, it suffers from the dc-link voltage ripple that causes it to merge with the third and fifth harmonics on the output current. For this reason, a very smooth dc-link voltage is essential in order to keep total harmonic distortion (THD) at a low level. However, the voltage ripple is inevitable in practise for single-phase inverters because of pulsating instantaneous power. This study presents a new volt-second-based current control method for flyback micro-inverters which improves THD caused by the voltage ripple. The proposed method works effectively up to approximately 20% of the dc-link voltage ripple. In addition, the volt-second-based control method is able to allow reduction of the power decoupling capacitor value. Experimental results validating the proposed method are also presented.

Sakata S.,Electronic Control Systems | Ashida F.,Electronic Control Systems | Tanaka H.,The University of Shimane
Computer Methods in Applied Mechanics and Engineering | Year: 2010

This paper discusses stabilization of an optimization procedure to determine an appropriate semivariogram parameter using the empirical semivariogram for Kriging-based approximation. From a viewpoint of a computational cost for constructing a surrogate model, a semivariogram fitting approach using the empirical semivariogram can be usable for the parameter estimation of a semivariogram function. However, instability of the optimization procedure for determination of the semivariogram parameter may be observed in some cases and it causes to generate an invalid surrogate model. For this problem, a simple technique for stabilization of the optimization for the parameter determination is proposed in this paper. The proposed approach employs a normalization technique of input data with respect to values of variables and an objective function. The proposed method is applied to some numerical examples, and the numerical results illustrate validity and effectiveness of the proposed method. © 2010 Elsevier B.V.

Sakata S.,Electronic Control Systems | Ashida F.,Electronic Control Systems | Kojima T.,Electronic Control Systems
Computers and Structures | Year: 2010

This paper describes a perturbation-based stochastic homogenization analysis method for a thermal expansion coefficient of a fiber reinforced composite material using the equivalent inclusion method. The proposed method is formulated for evaluation of the probabilistic characteristics of the homogenized thermal expansion coefficients considering uncertainties in material properties and geometry of a component material. As a numerical example, the probabilistic characteristics of the homogenized thermal expansion coefficients of a unidirectional fiber reinforced plastic are analyzed. With comparison between the results of the proposed method and the results of the Monte-Carlo simulation, validity, accuracy and effectiveness of the proposed method are investigated. © 2010 Elsevier Ltd. All rights reserved.

Ding Z.,Electronic Control Systems
International Journal of Control | Year: 2014

This paper deals with consensus control of a class of nonlinear systems with Lipschitz nonlinearities. Certain features of the Laplacian matrix are explored in the real Jordan form to identify conditions for global consensus control. Under the identified conditions, consensus control and stability of the proposed control are analysed in time domain through Lyapunov functions in real domain. The proposed control uses relative state information of the system. A simulation study is included to demonstrate the proposed control designs with some simulation results shown. © 2014 © 2014 Taylor & Francis.

Machida Y.,Electronic Control Systems | Funabiki S.,Electronic Control Systems
IEEJ Transactions on Power and Energy | Year: 2011

Output power in photovoltaic systems changes steeply with the change of the solar irradiance and overall PV temperature. The change of output power has influence on the electric power quality of the system. This paper proposes a novel operational scheme of the residential distributed power generation system using solar cells and hydrogen-storage type fuel cells. In order to level the output power which changes steeply the fuel cells are connected to the PV system in parallel. Thus the generated power of all the system can be leveled. However, the hydrogen is required in order to generate electricity by the fuel cells. Therefore, the electrolyzer which is hydrogen manufacturing equipment is installed in the system. It is confirmed by the simulation that the distributed power generation system operates according to the proposed operational scheme and its system is available for residential supplies. © 2011 The Institute of Electrical Engineers of Japan.

Lanzon A.,University of Manchester | Lanzon A.,Electronic Control Systems | Freddi A.,Marche Polytechnic University | Longhi S.,Marche Polytechnic University
Journal of Guidance, Control, and Dynamics | Year: 2014

In this paper, the problemof designingacontrol lawincase ofrotor failure inquadrotor vehiclesis addressed. First, a nonlinear mathematical model for a quadrotor vehicle is derived, which includes translational and rotational dynamics. Then a robust feedback linearization controller isdeveloped, which sacrifices the controllability ofthe yaw state due to rotor failure to linearize the closed-loop system around a working point, where roll and pitch angles are zero and the angular speed around the vertical axis is a nonzero constant. An H∞ loop shaping technique is adopted to achieve regulationofthese variables around the chosen working point. Finally,anouter loopisproposed for achieving control of the linear displacement under the assumption of small angles approximation for the pitch and roll angles. The proposed control strategy allows the vehicle to use the remaining three functional rotors to enter a constant angular speed around its vertical axis, granting stability and representing an effective way to deal with a rotor failure in quadrotor vehicles. Copyright © 2013 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Sakata S.,Electronic Control Systems | Ashida F.,Electronic Control Systems
Computational Mechanics | Year: 2011

This paper discusses a stochastic homogenization problem for evaluation of stochastic characteristics of a homogenized elastic property of a particle reinforced composite material especially in case of considering a nonuniform distribution of a material property or geometry of a component material and its random variation. In practice, some microscopic random variations in composites may not be uniform. In this case, a non-uniformly distributed random variation of a microscopic material or geometrical property should be taken into account. For this problem, this paper proposes a hierarchical stochastic homogenization method. This method assumes that a two-phase composite material can be separated into three-scales, and propagation of the randomness through the different scales can be evaluated with the perturbation-based technique. As an example, stochastic characteristics of homogenized elastic properties of a glassparticle reinforced plastic are estimated using the proposed approach.With the numerical results, importance of the problem and validity of the proposed method are discussed. © 2011 Springer-Verlag.

Vivero O.,Electronic Control Systems | Heath W.P.,Electronic Control Systems
Automatica | Year: 2012

There is significant interest in long-range dependent processes since they occur in a wide range of phenomena across different areas of study. Based on the available models capable of describing long-range dependence, various parameter estimation methods have been developed. In this paper we revisit the maximum likelihood estimator and its computationally efficient approximations: Whittle's Estimator and the Circulant Embedding Estimator. In particular, this paper proves the asymptotic properties of the Circulant Embedding estimator and establishes the asymptotic equivalence between the three estimators. Furthermore, it is shown that the three methods are ill-conditioned and thus highly sensitive to the presence of measurement errors. Finally, we introduce a regularisation method that improves the performance of the maximum likelihood methods when the datasets have been largely contaminated with errors. © 2011 Elsevier Ltd. All rights reserved.

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