Fossas Colet, Enric
Total activity: 293
Professional category
University professor
University degree
Matemáticas
Research group
ACES - Advanced Control of Energy Systems
Department
Department of Automatic Control
School
Barcelona School of Industrial Engineering (ETSEIB)
E-mail
enric.fossasupc.edu
Contact details
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1 to 50 of 293 results
  • Fixed frequency sliding mode-based robust inversion with a full-bridge current DC-link buck-boost

     Olm Miras, Josep Maria; Biel Sole, Domingo; Fossas Colet, Enric; Cardoner Parpal, Rafael
    Journal of the Franklin Institute
    Date of publication: 2014-01
    Journal article

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    The substitution of the original switches by a full bridge in a Non-Inverting Buck-Boost converter results in an inverter capable of carrying out step-down and step-up tasks as well under sliding mode control. The control law is implemented by means of the Zero Average Dynamics algorithm, which provides a fixed frequency operation and guarantees null error in each switching period, thus achieving a highly accurate tracking of periodic reference profiles. Furthermore, semi-infinite programming techniques are used to reduce power losses and, at the same time, prevent undesirable effects of control action saturation. The performance of the inverter is ensured to be robust in the face of bounded nonlinear and resistive loads. Realistic simulation results obtained with PSIMR software validate the proposed schemes.

  • A sliding mode controlled three wheeled narrow vehicle

     Fossas Colet, Enric; Roqueiro, Nestor; Gaudezi de Faria, Marcelo
    International journal of vehicle design
    Date of publication: 2013
    Journal article

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    This paper presents a sliding mode controller for a narrow tilting three-wheeled vehicle. The vehicle is modelled as a dynamic eighteen-order system with two inputs and two outputs, however, a simple third-order model of a bicycle is considered for design and analysis. The appropriateness of the simpler model for design purposes is verified through simulations. The designed trajectory control considers vehicle stability limits and takes advantage of the bicycle model flatness. Tilting and speed controllers are designed in the sliding mode framework through the analytical development of the bicycle model and simulated in the full eighteen-order system.

    This paper presents a sliding mode controller for a narrow tilting three-wheeled vehicle. The vehicle is modelled as a dynamic eighteen-order system with two inputs and two outputs, however, a simple third-order model of a bicycle is considered for design and analysis. The appropriateness of the simpler model for design purposes is verified through simulations. The designed trajectory control considers vehicle stability limits and takes advantage of the bicycle model flatness. Tilting and speed controllers are designed in the sliding mode framework through the analytical development of the bicycle model and simulated in the full eighteen-order system.

  • Sliding mode controlled multiphase buck converter with interleaving and current equalization

     Ramos Lara, Rafael Ramon; Biel Sole, Domingo; Fossas Colet, Enric; Griño Cubero, Roberto
    Control engineering practice
    Date of publication: 2013-05
    Journal article

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    This paper presents a sliding mode control design of a multiphase power converter. The use of multiphase converters and an appropriate phase shift result in chattering reduction to the desired level at a given switching frequency in the so called ¿ripple cancellation¿ or ¿harmonic cancellation¿. Additionally, this strategy considers sliding mode as a suitable substitute for Pulse Width Modulation because of the benefits in sliding mode control, i.e. the possibility of achieving desired system responses regardless of parameter changes. A 4-phase buck converter prototype was built and the controller was programmed in an FPGA. Experimental results show that chattering reduction, robust output regulation and phase current equalization are achieved, thus validating the proposed approach.

  • Bifurcation analysis of a Lyapunov-based controlled boost converter

     Spinetti Rivera, Mario de Jesús; Olm Miras, Josep Maria; Biel Sole, Domingo; Fossas Colet, Enric
    Communications in nonlinear science and numerical simulation
    Date of publication: 2013-11
    Journal article

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    Lyapunov-based controlled boost converters have a unique equilibrium point, which is globally asymptotically stable, for known resistive loads. This article investigates the dynamic behaviors that appear in the system when the nominal load differs from the actual one and no action is taken by the controller to compensate for the mismatch. Exploiting the fact that the closed-loop system is, in fact, planar and quadratic, one may provide not only local but also global stability results: specifically, it is proved that the number of equilibria of the converter may grow up to three and that, in any case, the system trajectories are always bounded, i.e. it is a bounded quadratic system. The possible phase portraits of the closed-loop system are also characterized in terms of the selected bifurcation parameters, namely, the actual load value and the gain of the control law. Accordingly, the analysis allows the numerical illustration of many bifurcation phenomena that appear in bounded quadratic systems through a physical example borrowed from power electronics.

    Lyapunov-based controlled boost converters have a unique equilibrium point, which is globally asymptotically stable, for known resistive loads. This article investigates the dynamic behaviors that appear in the system when the nominal load differs from the actual one and no action is taken by the controller to compensate for the mismatch. Exploiting the fact that the closed-loop system is, in fact, planar and quadratic, one may provide not only local but also global stability results: specifically, it is proved that the number of equilibria of the converter may grow up to three and that, in any case, the system trajectories are always bounded, i.e. it is a bounded quadratic system. The possible phase portraits of the closed-loop system are also characterized in terms of the selected bifurcation parameters, namely, the actual load value and the gain of the control law. Accordingly, the analysis allows the numerical illustration of many bifurcation phenomena that appear in bounded quadratic systems through a physical example borrowed from power electronics.

  • Cascade sliding mode-PID controller for a coupled-inductor boost converter

     Carrero Candelas, Niliana Andreina; Batlle Arnau, Carles; Fossas Colet, Enric
    IEEE Conference on Decision and Control
    Presentation's date: 2013-12
    Presentation of work at congresses

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    In this paper, a coupled-inductor Boost converter is modelled as a piece-wise complementarity system and controlled by means of two loops: a sliding mode control inner loop and an experimentally tuned PID outer loop control. The aim of the closed loop system is to regulate the output voltage of the coupled-inductor Boost converter. The control is carried out using the piece-wise complementarity model of the converter, which takes into account its hybrid dynamic. In addition, the performance and the effectiveness of the feedback control is validated through computer simulations using MATLAB and Psim.

  • Control en modo deslizante de un rectificador monofásico con un filtro LCL

     Biel Sole, Domingo; Doria Cerezo, Arnau; Fossas Colet, Enric
    Seminario Anual de Automática, Electrónica Industrial e Instrumentación
    Presentation's date: 2013-07-11
    Presentation of work at congresses

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    En este artículo se presenta el análisis dinámico y el diseño de un controlador para un rectificador monofásico controlado con un filtro LCL. El algoritmo de control está basado en las técnicas de modos deslizantes que permiten unas buenas prestaciones de seguimiento y robustez en los convertidores de potencia. Durante el diseño se ha considerado la conexión a una red débil y con fuerte contenido armónico. La ley de control se ha validado mediante simulaciones numéricas con resultados satisfactorios incluso en casos de una red no ideal.

  • Sliding mode control of a single-phase LCL full-bridge rectifier

     Biel Sole, Domingo; Doria Cerezo, Arnau; Fossas Colet, Enric
    Annual Conference of the IEEE Industrial Electronics Society
    Presentation's date: 2013-11-12
    Presentation of work at congresses

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    This paper presents a dynamic analysis and the control design for a singe-phase full bridge recti¿er with a LCL ¿lter. The control algorithm is based on the sliding mode control techniques that provides good tracking performances and robustness against parameter variations. The control design also considers the connection to a non ideal power network with a grid impedance as well as higher harmonics components in the voltage. The control law has been tested in numerical simulations with satisfactory results (also in the case of non ideal power grid).

  • Occurrence of Big Bang Bifurcations in Discretized Sliding-mode Control Systems

     Fossas Colet, Enric; Granados, Albert
    Differential equations and dynamical systems
    Date of publication: 2013
    Journal article

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  • Multi input sliding mode control of an autonomous fuel cell-supercapacitor hybrid system

     Moré, Jerónimo José; Puleston, Paul; Kunusch, Cristian; Fossas Colet, Enric
    International Workshop on Variable Structure Systems
    Presentation's date: 2012
    Presentation of work at congresses

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    This paper presents the design of a sliding mode control strategy through an input decoupling of an hybrid fuel cell based system. The hybrid system is composed by a fuel cell stack and a Supercapacitors module, connected to a single DC bus. A continuous conduction mode MIMO model is considered and the control strategy for the system is discussed. The latter is developed using a diffeomorphism to decouple the control inputs to surface interactions. Finally, an adaptive switching function for the two inputs is designed to robustly reject system perturbations and parameters variations. The control strategy is then evaluated through extensive simulation, considering strong load demand variations.

  • Sliding mode control with complementary inputs for a lean-burn IC engine

     Roqueiro, Nestor; Fossas Colet, Enric; Oliveira, Amir; Puleston, Paul
    International Workshop on Variable Structure Systems
    Presentation's date: 2012
    Presentation of work at congresses

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  • Diseño de un convertidor CC-CC doble boost acoplado

     González, Sergio; Puleston, Paul; Fossas Colet, Enric
    Congreso Argentino de Control Automático
    Presentation's date: 2012
    Presentation of work at congresses

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  • Modeling a coupled-inductor boost converter in the complementarity framework

     Carrero Candelas, Niliana Andreina; Batlle Arnau, Carles; Fossas Colet, Enric
    European Symposium on Computer Modeling and Simulation
    Presentation's date: 2012-11-16
    Presentation of work at congresses

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    We consider the modeling of switching circuits, consisting of passive elements, independent sources, which are subject both to externally induced switches (time events) and to state events. We focus on the use of the complementarity formalism for obtaining such hybrid (actually piecewise linear)models, assuming idealized current-voltage characteristics of the diodes and switches. In particular, a coupled-inductor Boost converter is modelled as a piece-wise complementarity system. We obtained also a discrete-time model which may be used for design and simulation purposes. In order to show the good performance of the model obtained, it is compared with the model of the converter obtained from the PSIM simulation software.

    We consider the modeling of switching circuits, consisting of passive elements, independent sources, which are subject both to externally induced switches (time events) and to state events. We focus on the use of the complementarity formalism for obtaining such hybrid (actually piecewise linear) models, assuming idealized current- voltage characteristics of the diodes and switches. In particular, a coupled-inductor Boost converter is modelled as a piece-wise complementarity system. We obtained also a discrete-time model which may be used for design and simulation purposes. In order to show the good performance of the model obtained, it is compared with the model of the converter obtained from the PSIM simulation software.

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    Harmonic balance-based control of a boost DC/AC converter  Open access

     Olm Miras, Josep Maria; Biel Sole, Domingo; Spinetti Rivera, Mario de Jesús; Fossas Colet, Enric
    International journal of circuit theory and applications
    Date of publication: 2012-08
    Journal article

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    The achievement of step-up inversion with a boost DC/AC converter requires appropriate periodic references for inductor currents, which have to satisfy ordinary differential equations (ODE) of the Abel type. These are equations with highly unstable solutions for which the existence of periodic solutions remains unproved. Hence, the studies reported so far in this subject obtain periodic output voltages that approximately track the expected profile using different periodic current references that do not exactly satisfy the Abel ODE. However, neither an explanation of why are periodic output voltages still obtained, nor an assessment of the output voltage error is provided. This paper analyzes the effect of using periodic current references in a Lyapunov-based controlled boost DC/AC converter performing step-up inversion tasks. It is shown that, for sufficiently accurate current references, the system exhibits asymptotically stable periodic solutions with bounded error. Moreover, the paper propounds the use of Harmonic Balance (HB)-based techniques to obtain such current references. Simulation and experimental results confirm that this choice yields periodic output voltages with an error that may be lowered using higher HB approximations.

  • Digital Repetitive Control Under Varying Frequency Conditions  Open access

     Ramos Fuentes, German Andres
    Defense's date: 2012-09-12
    Institute of Industrial and Control Engineering (IOC), Universitat Politècnica de Catalunya
    Theses

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    The tracking/rejection of periodic signals constitutes a wide field of research in the control theory and applications area and Repetitive Control has proven to be an efficient way to face this topic; however, in some applications the period of the signal to be tracked/rejected changes in time or is uncertain, which causes and important performance degradation in the standard repetitive controller. This thesis presents some contributions to the open topic of repetitive control working under varying frequency conditions. These contributions can be organized as follows: One approach that overcomes the problem of working under time varying frequency conditions is the adaptation of the controller sampling period, nevertheless, the system framework changes from Linear Time Invariant to Linear Time-Varying and the closed-loop stability can be compromised. This work presents two different methodologies aimed at analysing the system stability under these conditions. The first one uses a Linear Matrix Inequality (LMI) gridding approach which provides necessary conditions to accomplish a sufficient condition for the closed-loop Bounded Input Bounded Output stability of the system. The second one applies robust control techniques in order to analyse the stability and yields sufficient stability conditions. Both methodologies yield a frequency variation interval for which the system stability can be assured. Although several approaches exist for the stability analysis of general time-varying sampling period controllers few of them allow an integrated controller design which assures closed-loop stability under such conditions. In this thesis two design methodologies are presented, which assure stability of the repetitive control system working under varying sampling period for a given frequency variation interval: a mu-synthesis technique and a pre-compensation strategy. On a second branch, High Order Repetitive Control (HORC) is mainly used to improve the repetitive control performance robustness under disturbance/reference signals with varying or uncertain frequency. Unlike standard repetitive control, the HORC involves a weighted sum of several signal periods. With a proper selection of the associated weights, this high order function offers a characteristic frequency response in which the high gain peaks located at harmonic frequencies are extended to a wider region around the harmonics. Furthermore, the use of an odd-harmonic internal model will make the system more appropriate for applications where signals have only odd-harmonic components, as in power electronics systems. Thus an Odd-harmonic High Order Repetitive Controller suitable for applications involving odd-harmonic type signals with varying/uncertain frequency is presented. The open loop stability of internal models used in HORC and the one presented here is analysed. Additionally, as a consequence of this analysis, an Anti-Windup (AW) scheme for repetitive control is proposed. This AW proposal is based on the idea of having a small steady state tracking error and fast recovery once the system goes out of saturation. The experimental validation of these proposals has been performed in two different applications: the Roto-magnet plant and the active power filter application. The Roto-magnet plant is an experimental didactic plant used as a tool for analysing and understanding the nature of the periodic disturbances, as well as to study the different control techniques used to tackle this problem. This plant has been adopted as experimental test bench for rotational machines. On the other hand, shunt active power filters have been widely used as a way to overcome power quality problems caused by nonlinear and reactive loads. These power electronics devices are designed with the goal of obtaining a power factor close to 1 and achieving current harmonics and reactive power compensation.

  • Local and global phenomena in piecewise-defined systems: from big bang

     Granados Corsellas, Alberto
    Defense's date: 2012-09-17
    Department of Applied Mathematics I, Universitat Politècnica de Catalunya
    Theses

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    Control of a Stand-Alone Wound Rotor Synchronous Generator: Two Sliding Mode Approaches via Regulation of the d-Voltage Component  Open access

     Doria Cerezo, Arnau; Utkin, Vadim; Muñoz Aguilar, Raul Santiago; Fossas Colet, Enric
    IEEE transactions on control systems technology
    Date of publication: 2012-05
    Journal article

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    In this brief two sliding mode control alternatives to regulate the stator voltage amplitude for a stand alone wound rotor synchronous generator are presented. Both controllers use the stator voltage -component error in the sliding surface. In a first case an outer proportional-integral (PI) loop controller is added to provide the proper d-voltage component reference. The second approach consists in extending the dynamic system to include the integral term as state variable and to modify the former sliding surface by adding this new state. Finally, both simulations and experimental results validates the proposed algorithms

  • Two-fold singularity in nonsmooth electrical systems

     di Bernardo, Mario; Colombo, Alessandro; Fossas Colet, Enric
    IEEE International Symposium on Circuits and Systems
    Presentation's date: 2011-05-15
    Presentation of work at congresses

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  • Herramienta interactiva para el aprendizaje del control en modo de deslizamiento

     Carrero Candelas, Niliana Andreina; Costa Castelló, Ramon; Dormido Bencomo, Sebastián; Fossas Colet, Enric
    Jornadas de Automática
    Presentation's date: 2011-02-08
    Presentation of work at congresses

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    Control en modo deslizante para un convertidor reductor multifase en entrelazado con ecualización de corriente  Open access

     Ramos Lara, Rafael Ramon; Biel Sole, Domingo; Fossas Colet, Enric
    Seminario Anual de Automática, Electrónica Industrial e Instrumentación
    Presentation's date: 2011-07-06
    Presentation of work at congresses

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    La presente comunicación aplica la técnica de control en modo de deslizamiento para la obtención de robustez frente a variaciones de la tensión de entrada, de la carga y de la tensión de referencia en un convertidor reductor multifase. Con el objetivo de garantizar una correcta distribución de potencia entre las diversas fases se modifican adecuadamente las superficies de conmutación para lograr una ecualización de corrientes. De este modo el control propuesto permite regular la tensión de salida, lograr una correcta ecualización de corrientes y minimizar el rizado de corriente en el nodo de conexión de la carga. El diseño se valida mediante resultados de simulación.

  • Sliding mode controller and flatness based set-point generator for a three wheeled narrow vehicle

     Roqueiro, Nestor; G. de Faria, Marcelo; Fossas Colet, Enric
    World Congress of the International Federation of Automatic Control
    Presentation's date: 2011-09-01
    Presentation of work at congresses

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  • Big-bang bifurcations in a first order system with a relay

     Fossas Colet, Enric; Granados, Albert
    Conference on Dynamical Systems: Theory and Applications
    Presentation's date: 2011-12-08
    Presentation of work at congresses

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    In this work we describe the bifurcation scenario found in a general first order system when a relay based proportional control is considered. We show the existence of a big bang bifurcation causing the existence of an infinite number of period orbits near a co-dimension two bifurcation point

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    The ideal sliding dynamics of a stand alone synchronous generator  Open access

     Doria Cerezo, Arnau; Fossas Colet, Enric; Muñoz Aguilar, Raul Santiago
    European Nonlinear Dynamics Conference
    Presentation's date: 2011-07-24
    Presentation of work at congresses

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    The closes loop dynamics of a sliding-mode controlled stand alone synchronous generator with a resistive load is stuided in this paper. The resulting dynamics is piecewise continous, robust in front of parameter and load variations and performs a good regulacions of the output variable. In the ideal case we can find limit cycles tha may remain when actuators saturation effects are considered. Along the paper, numerical simulations and experimental results illustrate the complexity of the encountered behavior.

  • Two applications of sliding mode control in energy generation and power electronics

     Biel Sole, Domingo; Doria Cerezo, Arnau; Fossas Colet, Enric; Muñoz Aguilar, Raul Santiago; Ramos Lara, Rafael Ramon
    Date of publication: 2011-09-07
    Book chapter

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  • Técnicas de control avanzado para la mejora de la operación de convertidores vsi conectados a la red eléctrica

     Doria Cerezo, Arnau; Costa Castelló, Ramon; Olm Miras, Josep Maria; Fossas Colet, Enric; Biel Sole, Domingo; Orellana Barcelo, Marcos; Griño Cubero, Roberto
    Participation in a competitive project

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  • A feedback-based L-2-norm limiter for periodic signals

     Griño Cubero, Roberto; Ortega, Romeo; Fossas Colet, Enric
    Automatica
    Date of publication: 2011-01
    Journal article

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    Limiting the rms value (L2 norm) of periodic signals can be a necessity in some controllers for power electronic devices. The prevailing existing solution is simply to compute, off-line, the L2 norm and then to multiply the signal by the factor that ensures the desired bound is achieved. This feedforward procedure could yield unsatisfactory results during the transients of the system. In this paper, a feedback-based algorithm that carries out the computations on-line is proposed. Besides the on-line computation of the L2 norm, the second component of the algorithm is a classical proportional–integral loop with an anti-windup mechanism. Although the overall algorithm is described by complicated nonlinear, non-autonomous, delay-differential equations, a detailed stability analysis is carried out, proving its robust performance. Simulation results, that confirm the theoretical results, are presented.

  • Sliding mode control of a stand-alone wound rotor synchronous generator

     Muñoz Aguilar, Raul Santiago; Doria Cerezo, Arnau; Fossas Colet, Enric; Cardoner Parpal, Rafael
    IEEE transactions on industrial electronics
    Date of publication: 2011-10
    Journal article

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    This paper presents a sliding mode control for a wound rotor synchronous machine acting as an isolated generator. The standard dq model of the machine is connected to a resistive load. A switching function is defined in order to fulfill control objectives, and the ideal sliding dynamics is proved to be stable. From the desired surface, the standard sliding methodology is applied to obtain a robust and very simple controller. Numerical simulations and experimental results validate the control law and show good performance and a fast response to load and reference changes.

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    A sliding mode control for a wound rotor synchronous generator with an isolated RL load  Open access  awarded activity

     Muñoz Aguilar, Raul Santiago; Doria Cerezo, Arnau; Fossas Colet, Enric
    American Control Conference
    Presentation's date: 2010-07-01
    Presentation of work at congresses

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    In this paper a sliding mode controller for the stator voltage amplitude of a stand-alone wound rotor synchronous generator is presented. The standard dq-model of the electrical machine connected to an isolated inductive load is obtained. Then, a control law is designed in the framework of sliding mode control. The controller introduces a dynamic extension so that the stator amplitude relative degree is one. Numerical simulations are also presented to validate the presented control law.

    Best Presentation in Session Award, Americal Control Conference 2010

  • Herramienta interactiva para el aprendizaje del control en modo de deslizamiento en R22

     Carrero Candelas, Niliana Andreina; Costa Castelló, Ramon; Dormido Bencomo, Sebastián; Fossas Colet, Enric
    Jornadas CEA de Enseñanza a través de Internet-Web de la Ingeniería de Sistemas y Automática
    Presentation's date: 2010-06-03
    Presentation of work at congresses

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    Two sliding mode control approaches for the stator voltage amplitude regulation of a stand-alone WRSM  Open access

     Doria Cerezo, Arnau; Utkin, Vadim; Muñoz Aguilar, Raul Santiago; Fossas Colet, Enric
    International Workshop on Variable Structure Systems
    Presentation's date: 2010-06-28
    Presentation of work at congresses

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    In this paper two sliding mode control alternatives to regulate the stator voltage amplitude for a stand alone wound rotor synchronous generator are presented. Both controllers use the stator voltage d-component error in the sliding surface. In a first case an outer PI loop controller is added to provide the proper d-voltage component reference. The second approach consists in extending the dynamic system to include the integral term as state variable and to modify the former sliding surface by adding this new state. Finally, simulations results are done in order to validate the proposed algorithms.

  • Using interactive tools to teach/learn sliding mode control

     Carrero Candelas, Niliana Andreina; Costa Castelló, Ramon; Dormido Bencomo, Sebastián; Fossas Colet, Enric
    IEEE Conference on Decision and Control
    Presentation's date: 2010-12-15
    Presentation of work at congresses

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  • Sliding mode control multiphase buck converter implementation issues

     Biel Sole, Domingo; Fossas Colet, Enric; Ramos Lara, Rafael Ramon
    International Workshop on Variable Structure Systems
    Presentation's date: 2010-06
    Presentation of work at congresses

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    Two different approaches to achieve robustness with respect to the input voltage, the reference voltage and the load variations in a step-down multiphase power converter are presented in this paper. The proposal allows both to regulate the output voltage to a given reference and to minimize the current ripple. Design is validated by means of simulation results.

  • Virtual orbits and two-parameter bifurcation analysis in a ZAD-controlled buck converter

     Avrutin, Viktor; Fossas Colet, Enric; Granados, Albert; Schanz, Michael
    Nonlinear dynamics
    Date of publication: 2010-07-11
    Journal article

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  • Teixeira singularities in 3D switched feedback control systems

     Colombo, A.; di Bernardo, Mario; Fossas Colet, Enric; Jeffrey, M.R.
    Systems & control letters
    Date of publication: 2010-10
    Journal article

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    This paper is concerned with the analysis of a singularity that can occur in three-dimensional discontinuous feedback control systems. The singularity is the two-fold — a tangency of orbits to both sides of a switching manifold. Particular attention is placed on the Teixeira singularity, which previous literature suggests as a mechanism for dynamical transitions in this class of systems. We show that such a singularity cannot occur in classical single-input single-output systems in the Lur’e form. It is, however, a potentially dangerous phenomenon in multiple-input multiple-output switched control systems. The theoretical derivation is illustrated by means of a representative example.

  • Influence of reverse logistics on optimal manufacturing, remanufacturing, and storage capacities  Open access

     Benedito Benet, Ernest
    Defense's date: 2010-04-08
    Institute of Industrial and Control Engineering (IOC), Universitat Politècnica de Catalunya
    Theses

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    El propósito de la presente tesis es estudiar la influencia de la logística inversa en las capacidades de fabricación, refabricación y almacenaje óptimas de un sistema industrial. El interés por la logística inversa ha crecido en los últimos años de forma paralela a la preocupación, creciente también, por las cuestiones medioambientales en el mundo industrializado. En el capítulo 2 se hace una introducción a la logística inversa, explicando su definición y los motivos por los que se ha creado esta área de gestión diferenciada de la logística tradicional; se describen los tipos de productos que intervienen en la logística inversa y los distintos procesos para recuperar su valor. Además, se analizan las características del comportamiento de un sistema con logística inversa, comparándolas con las de un sistema tradicional. En el capítulo 3 se revisa la literatura tanto en el ámbito de la gestión de las capacidades de fabricación y almacenaje en un sistema tradicional como en el ámbito de la logística inversa. Para cumplir con el objetivo de la tesis, en los capítulos 4, 5 y 6 se estudian tres modelos de un sistema en que el producto recuperado es indistinguible del producto nuevo. El proceso seguido para realizar el estudio ha sido el mismo en cada uno de los modelos presentados: en primer lugar se ha determinado la política de producción óptima utilizando una cierta función de coste y suponiendo que tenemos dadas unas capacidades fijas, en segundo lugar se ha determinado el valor óptimo de las capacidades que optimizan la función de coste y en tercer lugar se estudian las variaciones de las cantidades óptimas al variar algunos parámetros relacionados con la logística inversa. En el capítulo 4 se pone de manifiesto cómo influye la aleatoriedad de los retornos en las capacidades óptimas estudiando un sistema con demanda uniforme y retornos aleatorios. La función de coste a optimizar es el valor esperado del coste en un periodo. En el capítulo 5 se estudia un modelo en el que la demanda y los retornos son funciones conocidas, continuas y periódicas. La función de coste a optimizar es el coste incurrido en el periodo y el problema de determinar la política de fabricación óptima es un problema de control óptimo. El modelo presentado permite analizar la variación en las capacidades óptimas al variar el plazo entre la venta y los retornos de los productos. En el capítulo 6 se trata un modelo con demanda y retornos aleatorios. La función de coste a optimizar es el valor esperado del coste en un periodo. Para realizar el cálculo de las políticas óptimas se hace la hipótesis de independencia estocástica de los retornos, comúnmente utilizada en la literatura. Una vez calculadas las capacidades óptimas se contrasta la validez de la hipótesis mediante simulación. El modelo se utiliza para estudiar la dependencia de las capacidades respecto de la probabilidad de que el producto sea retornado y respecto de los costes variables de refabricación. Finalmente en el capítulo 7 se recogen las conclusiones y los futuros temas de investigación.

    The purpose of this thesis is to study the influence of reverse logistics in optimal manufacturing, remanufacturing and storage capacities of an industrial system. The interest in reverse logistics has grown in recent years in parallel with the increasing concern about environmental issues in the industrialized world. In chapter 2, we provide an introduction to reverse logistics: explaining the definition of reverse logistics and the reasons for which has been created as a differentiated area of management of traditional logistics, describing the types of products involved in reverse logistics and the different processes to recover its value, and examining the behavioral characteristics of a reverse logistics systems, compared with the traditional logistics system. In chapter 3 we review the literature both in the field of capacity management in traditional systems and in the field of reverse logistics. To meet the objective of the thesis, we study three models of a system in which the recovered product is indistinguishable from the new product. The process followed for the study was the same in each of the models presented: firstly, we determine the optimal production policy for every value of capacities; the second step is determining the optimal value of the capacities when optimal policies are applied and third we study the dependency of optimal capacities on some parameters related with reverse logistics. In chapter 4 we study a system with uniform demand and random returns to show the influence of the randomness of returns in the optimal capacities. The cost function to optimize is the expected value of cost in a period. In chapter 5 we study a model in which demand and returns are known functions, continuous and periodic. The cost function to optimize is the cost incurred in the period and the problem of determining the optimal production policy is an optimal control problem. Using this model, we analyze the dependence of optimal capacity on the time between sales and product returns. In chapter 6 we present a stochastic model where demand and returns are sequences of random variables. The cost function to optimize is the expected value of cost in a period. To perform the calculation of optimal policies we assume that returns are stochastically independent of demand (this assumption is commonly used in the literature). The hypothesis is validated by simulation after optimal capacity is calculated. The model is used to study the dependence of the optimal capacities on the probability that the product is returned and also on the variable costs of remanufacturing. Finally in chapter 7 we discuss the conclusions and future research topics.

  • Sliding Mode Control of the Stand Alone Wound Rotor Synchronous Generator  Open access  awarded activity

     Muñoz Aguilar, Raul Santiago
    Defense's date: 2010-07-19
    Institute of Industrial and Control Engineering (IOC), Universitat Politècnica de Catalunya
    Theses

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    En esta Tesis ha sido analizado el control de la màquina sincrónica de rotor bobinado actuando en isla. Para esta configuración, la velocidad mecànica determina la frecuencia, y la tensión de rotor se utiliza para fijar la amplitud de la tensión de estator. Debido a que la constante de tiempo eléctrica es mucho más ràpida comparada con la constante de tiempo mecánica, la velocidad mecánica fue considerada constante y externamente regulada y la investigación se enfocó en la regulación de la amplitud de la tensión de estator.Cuatro diferentes controladores basados en técnicas de modos deslizantes fueron diseñados en el marco de referencia dq. Las leyes de control obtenidas regulan la amplitud de la tensión de estator independientemte del valor de la carga. Adicionalmente, sólo las medidas de tensión y posición del rotor (para calcular la transformada dq) son necesarias. La estabilidad de los puntos de equilibrio obtenidos fueron probados al menos utilizando anàlisis de pequeña señal.Se realizó la validación por simulación y experimental de cada controlador en diferentes escenarios. Los resultados obtenidos validan los diseños y muestran las principales ventajas y desventajas de el sistema en lazo cerrado.El capítulo 2 cubre los problemas de modelado de la màquina sincrónica de rotor bobinado. Partiendo de las ecuaciones trifásicas generales, y utilizando la transformada de Park, se encontraron el modelo en dq del generador sincrónico de rotor bobinado (WRSG) en isla, alimentando tanto carga resistiva como inductiva. Los puntos de equilibrio del sistema obtenido fueron analizados y calculados, luego se definió el objetivo de control. Finalmente, se obtuvieron modelos lineales aproximados y sus respectivas funciones de transferencia.Los controladores PI son los más usados en la industria porque ofrecen buen desempeño y son sencillos de implementar. En el capítulo 3, se obtuvieron las reglas de sintonización para el controlador PI, y se analizaron estos resultados con el objetivo de proponer nuevos controladores que mejoraran el desempeño de la clásica aproximación PI.El esquema de control en modos deslizantes para la WRSG conectada a una carga resistiva fue diseñado en el capítulo 4. Éste, también incluye un completo análisis de estabilidad del sistema en lazo cerrado. El capítulo 5 presenta dos diseños basados en modos deslizantes para regular la amplitud de la tensión de estator para el WRSG actuando en isla. Ambos diseños usan la componente d de la tensión de estator en la función de conmutación. El primer caso es un control anidado, donde un lazo externo PI es añadido para proveer la referencia de la componente d de la tensión. En la segunda aproximación un término integral es añadido a la superficie de conmutación.El caso de alimentar una carga inductiva es estudiado en el capítulo 6. El controlador requiere una extensión dinámica debido a que la amplitud de la tensión de estator es una salida de grado relativo cero. Como resultado, un controlador robusto, que no depende de los parámetros de la máquina ni de los valores de carga es obtenido. En el capítulo 7 los resultados de simulación y experimentales para los controladores diseñados para el WRSG actuando en isla son presentados. En primer lugar, una descripción completa del banco es presentada. Esta incluye detalles de la etapa de adquisición de datos y de la DSP utilizada. En segundo lugar, se hace la descripción del procedimiento de simulación. Luego, las simulaciones y experimentos, que contienen diferentes escenarios, con cambios de referencia y variaciones de carga para cada controlador son presentados.

    The control of the stand-alone the wound rotor synchronous generator has been analyzed in this dissertation. For this islanded configuration, the mechanical speed determines the frequency, and the rotor voltage is used to set the stator voltage amplitude. Due to the electrical time constant is so fast compared with the mechanical time constants, the mechanical speed was considered constant and externally regulated and the research was focused on the stator voltage amplitude regulation.Four different controllers based on sliding mode control techniques were designed in the dq reference frame. The obtained control laws regulate the stator voltage amplitude irrespectively of the load value. Furthermore, only voltage and rotor position measures (to compute the dq transformation), are required. The stability of the obtained equilibrium points was proved at least using small-signal analysis. Simulation and experimental validation of each controller containing several scenarios were carried out. The obtained results validate the designs and show the main advantages and disadvantages of each closed loop system. Chapter 2 covers the modeling issues of the wound rotor synchronous machine. From the general three-phase dynamical equations, and using the Park transformation, the dq-model of the stand-alone wound rotor synchronous generator feeding both a resistive and an inductive load are obtained. Equilibrium points of the obtained systems are analyzed and, after defining the control objective, the desired equilibrium points are computed.Finally, linear approximated models are obtained and their transfer functions are also presented.PI controllers are the most used in the industry because they offers good performance and are easily implementables. In Chapter 3 we obtain the tuning rule for the PI controller, and we analyze these results in order to propose new controllers which improve the classic PI approach.The sliding mode control scheme for the WRSG connected to a resistive load is designed in Chapter 4. It also includes a complete stability analysis of the closed loop system. Chapter 5 presents two sliding mode designs to regulate the stator voltage amplitude for a stand-alone wound rotor synchronous generator. Both use the stator voltage d-component error in the switching function. The first case is a nested controller, where an outer PI loop is added to provide the proper d-voltage component reference. In the second approach an integral term is added to the switching function. The case of feeding an inductive load is studied in Chapter 6. The controller introduces a dynamic extension because the stator voltage amplitude is a zero relative degree output. As result, a robust controller, which neither depends on the machine parameters nor on the load values, is obtained. In Chapter 7 the simulation and the experimental results of the designed controllers for the stand-alone wound rotor synchronous generator are presented. Firstly, a complete description of the bench is provided. It also includes details of the data acquisition stage and the used DSP card. Secondly, the description of the simulation procedure is commented. Then, the simulation and experiments which contains several scenarios, with reference change and load variations evaluated for each controller are presented.

  • Best Presentation in Session Award at the 2010 American Control Conference (2010 ACC ThA)

     Muñoz Aguilar, Raul Santiago; Doria Cerezo, Arnau; Fossas Colet, Enric
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  • Two-parameter bifurcation curves in power electronic converters

     Fossas Colet, Enric; Hogan, Stephen John; Martinez-seara Alonso, Maria Teresa
    International journal of bifurcation and chaos
    Date of publication: 2009-01
    Journal article

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  • Robust Linear Control of DC-DC Converters.

     Olalla Martínez, Carlos
    Defense's date: 2009-06-16
    Institute of Industrial and Control Engineering (IOC), Universitat Politècnica de Catalunya
    Theses

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  • Access to the full text
    Sliding mode control of an isolated wound rotor synchronous generator  Open access

     Doria Cerezo, Arnau; Fossas Colet, Enric; Muñoz Aguilar, Raul Santiago; Utkin, Vadim
    European Control Conference
    Presentation's date: 2009-08-23
    Presentation of work at congresses

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    Some experiments on chattering suppression in power converters  Open access

     Biel Sole, Domingo; Fossas Colet, Enric
    IEEE International Conference on Control Applications
    Presentation's date: 2009-07-08
    Presentation of work at congresses

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    This paper contains some experiments based on the paper Chattering Suppression in Multiphase Power Systems by Hoon Lee, Andrey Malinin, and Vadim I. Utkin that will appear in International Journal of Control. In that paper, the use of multi-phase converters and an appropriated phase shift allows reducing chattering to desired level under given switching frequency in the so called “ripple cancelation” or “harmonic cancelation”. Additionally this strategy would consider sliding mode as a suitable substitute over the Pulse Width Modulation because of the benefits in sliding mode control, e.g. the ability to achieve desired system responses regardless of a certain level of parameter changes. A half-bridge buck converter prototype was built and the chattering suppression reported in the Hoon Lee at al. paper has been checked comparing the power converter performances operating with 1-phase and 4-phases respectively.

  • A functional iterative approach to the tracking control of nonminimum phase switched power converters

     Fossas Colet, Enric; Olm Miras, Josep Maria
    Mathematics of control signals and systems
    Date of publication: 2009-12
    Journal article

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  • Sliding-mode control design applied to parallel-connected modular inverters through FPGA-based implementation

     Ramos Lara, Rafael Ramon; Biel Sole, Domingo; Fossas Colet, Enric; Guinjoan Gispert, Francisco
    IET control theory and applications
    Date of publication: 2009-12
    Journal article

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    High-Performance Control of a Single-Phase Shunt Active Filter  Open access

     Costa Castelló, Ramon; Griño Cubero, Roberto; Cardoner Parpal, Rafael; Fossas Colet, Enric
    IEEE transactions on control systems technology
    Date of publication: 2009-11
    Journal article

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    Shunt active power filters are devices, connected in parallel with nonlinear and reactive loads, which are in charge of compensating these characteristics in order to assure the quality of the distribution network. This paper analyzes the dynamics of a dc bus split-capacitor boost converter used as an active filter and proposes a control system which guarantees the desired closedloop performance (unity power factor and load-current harmonics and reactive-power compensation). The proposed controller is hierarchically decomposed into two control loops, one in charge of shaping the network current and the other in charge of assuring the power balance. Unlike previous works that appeared in the literature, both control loops are analytically tuned. This paper describes the analytical design of the controller and presents some experimental results that show the good performance of the closedloop system.

  • Port-Based Modeling in Different Domains

     Batlle Arnau, Carles; Doria Cerezo, Arnau; Fossas Colet, Enric
    Date of publication: 2009-08-19
    Book chapter

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  • ALGORITMOS PARA LA REDUCCIÓN DE ORDEN Y CONTROL DE SISTEMAS INTERCONECTADOS DE GRAN DIMENSIÓN

     Ras Sabido, Antoni; Massana Hugas, Immaculada; Simo Mezquita, Ester; Fossas Colet, Enric; Franch Bullich, Jaime; Prat Farran, Joana d'Arc; Riego Pérez, Albert; Batlle Arnau, Carles
    Participation in a competitive project

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  • ACES CONTROL AVANÇAT DE SISTEMES D'ENERGIA

     Serra Prat, Maria; Riera Colomer, Jordi; Batlle Arnau, Carles; Olm Miras, Josep Maria; Biel Sole, Domingo; Griño Cubero, Roberto; Doria Cerezo, Arnau; Costa Castelló, Ramon; Sarmiento Carnevali, Maria Laura; Franch Bullich, Jaime; Fossas Colet, Enric
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  • Iterative approximation of limit cycles for a class of Abel equations

     Fossas Colet, Enric; Olm Miras, Josep Maria; Sira Ramírez, Hebertt J.
    Physica. D, Nonlinear phenomena
    Date of publication: 2008-12
    Journal article

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  • Bounding the Output Error in a Buck Power Converter Using Perturbation Theory

     Fabiola, Angulo; Fossas Colet, Enric; Martinez-seara Alonso, Maria Teresa; Gerard, Tere M Seara And Olivar
    Mathematical problems in engineering
    Date of publication: 2008-10
    Journal article

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  • Modelado y Análisis de un Convertidor Elevador con Inductancias Acopladas

     Lisbeth, C Pérez; Fossas Colet, Enric; González, Sergio; Malo Barragan, Shane Leonardo; Puleston, Paul
    XIII Congreso Latinoamericano de Control Automático
    Presentation of work at congresses

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