Fuel cells are an attractive option for alternative power and of use in a variety of applications. This paper proposes a state space model for the solid oxide fuel cell (SOFC) based power system that comprises fuel cell, DC-DC buck converter, and load. In this investigation we have taken up a case study for SOFC feeding a DC load where a DC-DC buck converter acts as the interface between the load and the source. A proportional-integral (PI) controller is used in conjunction with pulse width modulation (PWM) that computes the pulse width and switches the MOSFET at the right instant so that the desired voltage is obtained. The proposed model is validated through extensive simulation using MATLAB/SIMULINK. Controller for the fuel cell power system (FCPS) is prototyped using XC3S500E development board containing a SPARTAN 3E Xilinx FPGA that simplifies the entire control circuit besides providing additional flexibility for further improvement. The results clearly indicate improved performance and validate our proposed model. 1. Introduction Nowadays, people depend on electrical energy more than ever; thus the importance of generating electrical energy increases significantly. Fuel cells are alternative power sources that have recently attracted a great deal of attention. Fuel cell generates dc voltage from the chemical reaction of hydrogen and oxygen and the by-products are water and heat [1–3]. Fuel cell can serve as another source of energy in the event of power outage. People use fuel cells in a vast range of applications because of their clean and efficient way of supplying electric power. The fuel cells are used in standalone purposes at homes, schools, and hospitals and in numerous vehicles. Different types of fuel cells exist in the world. From these fuel cells, solid oxide fuel cell (SOFC) is an important one [4, 5] because of its high efficiency and solid material (electrolytic material is ceramic) it uses. In SOFC, electric power is generated by passing hydrogen gas from anode and oxygen from cathode. There is an electrolyte between anode and cathode which fastens the electric charge as shown in Figure 1 [6]. In modelling a fuel cell powered system, it is necessary to optimize not only the design of the SOFC but also the related power conditioning circuits along with required controllers. Mainly, these conditioning circuits include a DC-DC converter and a load. The DC-DC converter is designed to convert the unregulated DC output voltage of the SOFC to a lower/higher and stable DC voltage. Many researchers have proposed fuzzy logic control (FLC)
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