Resumen de Design and Control of an Electric Energy Conditioning System for a PEM Type Fuel Cell
Isolated electric energy generation systems are often needed to supply electric loads where the electrical network is not available. This could be caused due to geographic isolation, the necessity of load mobility, demanded values of voltage and current that are not compatible with the local networks, etc. This makes the design and construction of stand-alone energy generation systems a must.Modern designs are being pushed towards cleaner technologies. The experience has shown that the usual methods employed to produce electrical energy are not sustainable, especially because of environmental concerns. Usual stand-alone energy generation systems employ batteries and fuel engines. Batteries offer a cheap mean to feed the generation system but need rigorous maintenance routines, the substances used in their construction are strong pollutants, offer relatively low durability and the ratio charge time/discharge time is too high. Fuel engines extract their energy from petroleum based fuels, and as its well known, pollute their surrounding environment in several ways producing smoke, noise and heat.Polymer electrolyte membrane type fuel cells are among the new technologies that are being considered as a good alternative to the traditional power sources used for stand-alone energy generation systems.AIthough the basic principles of operation of the fuel cells are known since 1839, this is a technology that is far from being mature. More work needs to be done in order to make of the fuel cells systems with, high reliability, with maximum efficiency, and capable of providing electrical energy with quality comparable to the quality achieved using usual methods.The problems when working with fuel cells can be split in two big groups of interest, the first, being the handling and control of the electrochemical variables, and the second, the handling and control of the electrical variables taking care of the limits imposed by the dynamics of the fuel cell unit. This work deals with the second group of concerns, looking at the fuel cell as a black-box dc power supply with certain current/voltage characteristics. The energy provided by the fuel cells needs to be conditioned to the levels and characteristics required by the loads to be fed. In Europe, for single-phase ac loads, the specifications are a sinusoidal output voltage with 230 V ac rms and a frequency of 50 Hz. This work presents the the analysis, design, construction, and control of the electric energy conditioning system for a polymer eIectrolyte membrane type fuel cell to act as an stand-alone dc-ac inverter to feed linear or nonlinear loads with big variations.
