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

Passivity and robust PI control of the air supply system of a PEM fuel cell model

Fuel cells are electrochemical devices that convert the chemical energy of a gaseous fuel directly into electricity. They are widely regarded as potential future stationary and mobile power sources. The response of a fuel cell system depends on the air and hydrogen feed, flow and pressure regulation, and heat and water management. In this paper, the study is concentrated on the control of the air subsystem that feeds the fuel cell cathode with oxygen—whose dynamics is described with a widely accepted nonlinear model. Due to the complexity of this model, the model-based controllers that have been proposed for this application are designed using its linear approximation at a given equilibrium point, which might lead to conservative stability margin estimates for the usually wide operating ranges of the system. On the other hand, practitioners propose the use of simple proportional or proportional–integral controllers around the compressor flow, which ensures good performance in most applications. In this paper we provide the theoretical justification to this scheme, proving that this output variable has the remarkable property that the linearization (around any admissible equilibrium) of the input–output map is strictly passive. Hence, the controllers used in applications yield (locally) asymptotically stable loops—for any desired equilibrium point and all values of the controller gains. Ensuring stability for all tuning gains overcomes the inherent conservativeness of linearized dynamics analysis, and assures the designer on the current use of robust, high performance loops. Instrumental to prove the passivity property is the exploitation of some monotonicity characteristics of the system that stem from physical laws

Diseño de un controlador PI no lineal para el suministro de aire de una pila de combustible

XXVIII JORNADAS DE AUTOMÁTICA. 05/09/2007. HuelvaEl presente documento muestra el dise˜no de un controlador jer´arquico para regular la tasa de exceso de ox´ıgeno de una pila de combustible. El controlador esclavo, un PI no lineal, estabiliza el flujo de aire en el compresor y permite un seguimiento de referencia. Un segundo controlador, el maestro, calcula la referencia del flujo de aire que utiliza el controlador esclavo para estabilizar la tasa de exceso de ox´ıgeno en un valor de 2. Este esta compuesto por un control de preal- ´ imentaci´on din´amica m´as un PI lineal para evitar errores en r´egimen estacionario. La estrategia de control se aplica a un modelo matem´atico de una pila de combustible y se presentan resultados de las simulaciones.Ministerio de Eduación y Ciencia DPI-2004-07444-C04-0

A review on existing modelling methodologies for PEM Fuel Cell Systems

International audienceThis paper is a common review research paper written in the framework of the "Energy program" of the French National Centre for Scientific Research (CNRS). In this program, funding has been provided to a project aiming to federate all the French competencies around fuel cell systems. Thus, as a first achievement, a review on existing modelling methodologies for PEM fuel cell systems is here proposed