Control of oxygen excess ratio in a PEM fuel cell system using high-order sliding-mode controller and observer

The main objective of this manuscript is to design a high-order sliding-mode observer to provide finite time estimation of unmeasurable states (x4 : oxygen mass, x5 : nitrogen mass) together with the oxygen excess ratio (ratio of the input oxygen ow to the reacted oxygen ow in the cathode). This is done by applying second-order sliding modes through either super twisting or suboptimal controllers to control the proton exchange membrane fuel cell's breathing. The estimated oxygen excess ratio is controlled in a closed-loop system using 2 distinct sliding-mode approaches: a cascaded super twisting controller and a single-loop suboptimal structure. Simulation results are presented to make a quantitative comparison between the cascade and the single-loop configuration. The results verify that the cascade provides accurate reference tracking while the single-loop presents faster convergence

Robust control design for air breathing proton exchange membrane fuel cell system via variable gain second-order sliding mode

The nonlinear and time-dependent characteristic and unknown modeling uncertainty of proton exchange membrane fuel cell (PEMFC) such as complex electro-chemical, thermal, and fluid mechanic phenomena make its controller design quite challenging. In this paper, a controller based on a super twisting algorithm (STA) with variable gains is proposed to control the air breathing system of PEMFC. The strategy includes regulating the oxygen excess ratio ((Formula presented.)) for preventing the stack oxygen starvation and maintaining optimum net power output in spite of external disturbances and model uncertainties. The proposed algorithm has the main advantages of the fixed gain STA, such as robustness against the disturbance and parametric uncertainties with the unknown boundary, chattering reduction, and finite time convergence. The Lyapunov analysis was proposed to assess the stability of the Variable Gain Super Twisting Algorithm (VGSTA). The results verified the effectiveness of the proposed controller with attaining robust regulation against uncertainties, disturbances, and noisy circumstance compared to fixed gain SOSM controllers

Robust feedback linearization control of air-feed system in PEM fuel cell against practical uncertainty

In this paper robust feedback linearization control approach based on the gap metric analysis is proposed to control a Proton Exchange Membrane Fuel Cell (PEMFC). The oxygen excess ratio ( ) is regulated through adjustment of the air supply to avoid oxygen starvation. Furthermore regulation improves the efficiency whilst more net power will be delivered. In this paper a six order state variable PEM fuel cell is used as a plant whereas the system variations and disturbances are regarded as uncertainties to configure the perturbed plant. The gap metric analysis is gained in this paper to assess the difference between the perturbed plants and that of the nominal. Results of using the nonlinear control law reveal that the proposed feedback linearization control is robust against disturbances during the oxygen excess ratio regulation.Results verify that the measurement delays in super twisting algorithm excite un-modeled dynamics because of higher frequency in the oscillations. The proposed controller eliminates influence of un-modeled dynamic and delay of actuator and sensor. Furthermore the designed controller is found capable to attenuate the practical measurement noise effect (in terms of a stochastic uncertainty) in both of the frequency spectrum and also in the overall amplitude

Identification of PEM fuel cells based on support vector regression and orthonormal bases

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Polymer Electrolyte Membrane Fuel Cells (PEMFC) are efficient devices that convert the chemical energy of the reactants in electricity. In this type of fuel cells, the performance of the air supply system is fundamental to improve their efficiency. An accurate mathematical model representing the air filling dynamics for a wide range of operating points is then necessary for control design and analysis. In this paper, a new Wiener model identification method based on Support Vector (SV) Regression and orthonormal bases is introduced and used to estimate a nonlinear dynamical model for the air supply system of a laboratory PEMFC from experimental data. The method is experimentally validated using a PEMFC system based on a ZB 8-cell stack with Nafion 115 membrane electrode assembliesPeer ReviewedPostprint (author's final draft

Contribution à la commande non linéaire robuste des systèmes d'alimentation en air des piles à combustible de type PEM

La pile à combustible (PàC) est un dispositif qui produit de l'électricité à partir d'une réaction chimique entre l'hydrogène et l'oxygène. Le système à PàC nécessite un certain nombre d'auxiliaires pour fonctionner. Pour cela, un système de commande est indispensable pour optimiser la performance de la PàC.Dans ce travail de thèse, nous nous sommes intéressés à trois types de problématiques de commande de la PàC. La première est celle de l'optimisation de la puissance délivrée par la PàC en contrôlant le rapport d'excès d'oxygène via le débit d'air du compresseur ; en prenant en compte les variations paramétriques, les incertitudes et les perturbations externes. Ce problème est résolu en utilisant la commande non-linéaire par mode glissant d'ordre 2. Deux types d'algorithme sont synthétisés, l'algorithme du mode glissant d'ordre 2 sous-optimal et l'algorithme du Super Twisting adaptatif. Les performances de ces lois de commande ont été validées grâce à un simulateur Hardware In Loop. La deuxième concerne la maximisation de la puissance nette fournie par la pile, tout en maintenant le fonctionnement du compresseur centrifuge dans sa zone nominale et tout en évitant le manque d'oxygène à la cathode, lors des variations rapides de charge. La solution proposée pour résoudre ce problème est un gestionnaire de charge qui consiste en un filtre à coefficient de filtrage ajustable. Deux approches d'ajustement de ce coefficient basées sur la technique de l'Extremum Seeking sont appliquées, comparées et validées expérimentalement. La troisième problématique abordée dans cette thèse est celle de la régulation de la différence de pression entre l'anode et la cathode, lors de variations de charge en présence de variations paramétriques et d'incertitudes. Une solution basée sur un contrôleur multi-variable par mode glissant d'ordre 2 associé à une étude de robustesse est proposée.The PEM fuel cell is a device which generates electricity from a chemical reaction between hydrogen and oxygen. The PEM fuel cell requires many ancillaries to operate the system. A control system is needed to optimize the performance of the PEMFC. This thesis is focused upon three specific control problems related to PEM fuel cell systems. The first problem is the control of the air (oxygen source) entering in the cathode side of fuel cell. The objective is to regulate the oxygen excess ratio in order to maintain the optimum net power output. This problem has been addressed using nonlinear second order sliding mode controllers, which are robust against parametric uncertainty and external disturbance. The SOSM controllers are based on two algorithms: sub-optimal and adaptive Super Twisting. Their performance is validated through Hardware In Loop simulation. The second problem is to maintain the centrifugal compressor in its operating zone, while avoiding the oxygen starvation in the cathode side during rapid load variations. The proposed solution to this problem is a load governor, which is similar to a variable bandwidth first order linear filter. Two adjustment algorithms have been applied for the bandwidth coefficient, based on the Extremum Seeking technique. Their performance has been validated experimentally. The third problem addressed in this thesis is the regulation of the pressure difference between the anode and the cathode during load variations. The control objective is achieved using second order sliding mode MIMO controller, which has been shown to be robust against parametric uncertainty and external disturbance.BELFORT-UTBM-SEVENANS (900942101) / SudocSudocFranceF

Constraint-Aware and Efficiency-Aware Control of Air-Path in Fuel Cell Vehicles

Fuel cell technology offers the potential for clean, efficient, robust energy productionfor both stationary and mobile applications. But without fast and robust control systems, fuel cells cannot hope to maintain real-life efficiencies near enough to their theoretical potential. This work studies control and constraint management techniques to regulate a nonlinear multivariable air-path system for a proton exchange membrane fuel cell (PEMFC). The control objectives are to avoid oxygen starvation, run at the maximum net efficiency, achieve fast tracking of air flow and pressure set-points, and be easy to calibrate. To operate at maximum efficiency, a set-point map is generated for air pressure at the cathode inlet. Considering that the conventional PEMFC system cannot independently control the inlet pressure using only the compressor motor, a new multivariable analysis and control scheme is formulated by considering an electronic throttle body (ETB) valve downstream of the cathode as a new degree of freedom in the control problem. Based on this new configuration of the fuel cell model, an internal model control (IMC) controller is designed with intuitive tuning parameters to simultaneously control airflow and pressure, and achieves a fast and smooth response despite strongly coupled plant dynamics. Further, a reference governor (RG) using a computationally tractable linear prediction model is included with IMC-based Multi-Input Multi-Output (MIMO) controller to satisfy the constraint on oxygen level. Compared with a Single-Input Single-Output (SISO) air-flow control approach, the proposed MIMO control approach demonstrated up to 7.36 percent lower hydrogen fuel consumption

Pem fuel cell modeling and converters design for a 48 v dc power bus

Fuel cells (FC) are electrochemical devices that directly convert the chemical energy of a fuel into electricity. Power systems based on proton exchange membrane fuel cell (PEMFC) technology have been the object of increasing attention in recent years as they appear very promising in both stationary and mobile applications due to their high efficiency, low operating temperature allowing fast startup, high power density, solid electrolyte, long cell and stack life, low corrosion, excellent dynamic response with respect to the other FCs, and nonpolluting emissions to the environment if the hydrogen is obtained from renewable sources. The output-voltage characteristic in a PEMFC is limited by the mechanical devices which are used for regulating the air flow in its cathode, the hydrogen flow in its anode, its inner temperature, and the humidity of the air supplied to it. Usually, the FC time constants are dominated by the fuel delivery system, in particular by the slow dynamics of the compressor responsible for supplying the oxygen. As a consequence, a fast load transient demand could cause a high voltage drop in a short time known as oxygen starvation phenomenon that is harmful for the FC. Thus, FCs are considered as a slow dynamic response equipment with respect to the load transient requirements. Therefore, batteries, ultracapacitors or other auxiliary power sources are needed to support the operation of the FC in order to ensure a fast response to any load power transient. The resulting systems, known as FC hybrid systems, can limit the slope of the current or the power generated by the FC with the use of current-controlled dc-dc converters. In this way, the reactant gas starvation phenomena can be avoided and the system can operate with higher efficiency. The purpose of this thesis is the design of a DC-DC converter suitable to interconnect all the different elements in a PEMFC-hybrid 48-V DC bus. Since the converter could be placed between elements with very different voltage levels, a buck-boost structure has been selected. Especially to fulfill the low ripple requirements of the PEMFCs, but also those of the auxiliary storage elements and loads, our structure has inductors in series at both its input and its output. Magnetically coupling these inductors and adding a damping network to its intermediate capacitor we have designed an easily controllable converter with second-order-buck-like dominant dynamics. This new proposed topology has high efficiency and wide bandwidth acting either as a voltage or as a current regulator. The magnetic coupling allows to control with similar performances the input or the output inductor currents. This characteristic is very useful because the designed current-controlled converter is able to withstand shortcircuits at its output and, when connected to the FC, it facilitates to regulate the current extracted from the FC to avoid the oxygen starvation phenomenon. Testing in a safe way the converter connected to the FC required to build an FC simulator that was subsequently improved by developing an emulator that offered real-time processing and oxygen-starvation indication. To study the developed converters and emulators with different brands of PEMFCs it was necessary to reactivate long-time inactive Palcan FCs. Since the results provided by the manual reactivation procedure were unsatisfactory, an automatic reactivation system has been developed as a complementary study of the thesis.En esta tesis se avanzo en el diseño de un bus DC de 48 V que utiliza como elemento principal de generación de energía eléctrica una pila de combustible. Debido a que la dinámica de las pilas de combustible están limitadas por sus elementos mecánicos auxiliares de control una variación rápida de una carga conectada a ella puede ocasionar daños. Es por esto que es necesario utilizar elementos almacenadores de energía que puedan suministrar estas rápidas variaciones de carga y convertidores para que gestionen de una forma controlada la potencia del bus DC. Durante la realización de pruebas de los convertidores es de gran importancia utilizar emuladores o simuladores de pilas de combustibles, esto nos permite de una forma económica y segura realizar pruebas criticas antes de conectar los convertidores a la pila. Adicionalmente una nueva topologia de convertidor fue presentada y ésta gestionará la potencia en el bu

Pregled znanstvenih napredaka u učinskoj elektronici usmjerenih ka osiguravanju efikasnog rada i dužeg životnog vijeka PEMgorivih ćelija

This article focuses on the main issues that affect the lifetime and performance of proton-exchange membrane fuel cells. The short lifespans of these fuel cells represent a barrier to their massive commercialization and usage in mobile and stationary applications. As fuel cell is a very complex system, a lot of knowledge of different areas is required, such as chemistry, electricity and mechanics, in order to completely understand its operation and all the problems that can occur during it. It is for this reason that an interdisciplinary approach needs to be taken when designing fuel-cell energy systems. This paper focuses on identifying and solving those issues that negatively affect the lifetime and performance of fuel cells. It is hoped that this article would be a valuable aid for power electronics’ researchers and engineers for better understanding the presented issues and a useful guide for solving them with the use of proper power electronic-devices. Initially, the basic operation and structure of a proton-exchange membrane fuel cell is explained. Three main issues that can occur during operation of a mobile or stationary fuel cell energy system are pointed out and discussed in details, on the basis of the state-of-the-art on fuel cell technology. These issues are poor water management, reactant gas starvation and fuel cell current ripple. This article provides answers as to why they occur, how they affect the fuel cell, how they can be mitigated, and what are the future trends within this research field.Članak se osvrće na ključna pitanja koja utječu na vrijeme rada i performanse gorivih ćelija s polimernom membranom kao elektrolitom. Kratak životni vijek gorivih ćelija takve vrste prepreka je njihovoj komercijalizaciji i masovnoj upotrebi u mobilnim i stacionarnim stanicama. Budući da su gorive ćelije komplicirani sustavi potrebno je znanje iz raznih područja kemije, elektrotehnike i mehanike da bi se u potpunosti mogao razumjeti njihov način rada i problemi koji se događaju. Upravo je zbog toga multidisciplinarni pristup nužnost pri razvoju sustava koji koriste gorive ćelije. Ovaj je članak usmjeren prema identifikaciji i rješavanju onih problema koji negativno utječu na životni vijek i performanse gorivih ćelija. Autori se nadaju da će se članak pokazati kao korisna pomoć i vodič istraživačima i inženjerima u domeni učinske elektronike pri susretu s navedenim problemima. Objašnjen je način rada i struktura gorive ćelije s polimernom membranom kao elektrolitom. Izložena su, i diskutirana do u detalje, tri glavna problema sa stajališta trenutačnih spoznaja u području učinske elektronike. Ti problemi su: loše upravljanje vodom, nestanak reaktantnog plina i strujni trzaji u gorivim ćelijama. Objašnjeno je zašto se ovi problemi događaju, kako utječu na gorivu ćeliju, kako ih se može spriječiti i koje su buduće perspektive istraživanja

Multibody dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: Formulations and Numerical Methods, Efficient Methods and Real-Time Applications, Flexible Multibody Dynamics, Contact Dynamics and Constraints, Multiphysics and Coupled Problems, Control and Optimization, Software Development and Computer Technology, Aerospace and Maritime Applications, Biomechanics, Railroad Vehicle Dynamics, Road Vehicle Dynamics, Robotics, Benchmark Problems. The conference is organized by the Department of Mechanical Engineering of the Universitat Politècnica de Catalunya (UPC) in Barcelona. The organizers would like to thank the authors for submitting their contributions, the keynote lecturers for accepting the invitation and for the quality of their talks, the awards and scientific committees for their support to the organization of the conference, and finally the topic organizers for reviewing all extended abstracts and selecting the awards nominees.Postprint (published version

Actas de las XXXIV Jornadas de Automática

Postprint (published version