Control of solid oxide fuel cell for stand-alone and grid connection using fuzzy logic technique

Fuel cells are very promising sources of electricity; environmentally safe and very efficient. The fuel cells have numerous applications: houses, industries, hospitals, vehicles etc. Another facet of these fuel cell applications is distributed generation, the implementation of various power generating resources, near the site of need, for reducing reliance on grid power. Fuel cells generate electricity from hydrogen by a chemical process. In this paper a solid oxide fuel cell mathematical model is adopted. The solid oxide fuel cells are very efficient and the technology is most suited to applications in the distributed generation. The main aim of the paper is to achieve the control of the fuel cell for stand-alone and grid connection. To achieve a grid interface and stand-alone working by designing suitable power conditioning units. The power conditioning unit is needed for the processing of the raw power output of the fuel cell in order to make it usable. The power conditioning unit might consist of only a DC/DC converter or the two stages of a DC/DC converter and a DC/AC inverter. For the stand-alone part the concentration is on the controlled DC power thus, only a boost converter (DC/DC) stage is used. For the grid interface of the solid oxide fuel cell controlled AC power is needed at the interface point, thus, both stages; boost converter as well as the inverter (DC/AC) are needed. A power conditioning unit is designed for this solid oxide fuel cell and for fuel cells in general. The fuzzy logic control strategy is used for designing the controllers.