The design of the inverter output filter of a fuel cell power plant in an isolated system

The operation of a solid-oxide fuel cell (SOFC) as an isolated generator is considered. A simplified dynamic model for a SOFC plant, in the form of an equivalent electrical circuit, is derived. The model is then used in the design of an output filter stage in which harmonic distortions are controlled. The design criterion of the filter is primarily based on controlling the total harmonic distortion of the load voltage and the inverter output current. Furthermore, the filter power loss is also kept below an acceptable value. Based on the theoretical analysis and the analytical expressions obtained, a design procedure for the filter is proposed. Simulation result is given to verify the proposed design approach.