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Abstract-This paper presents the dynamics of a phosphoric acid fuel cell (PAFC) and its associated power electronics. The modeling of the power conditioning system for phosphoric acid fuel cell is discussed here. This model is based on empirical equations. The simulation is done using Matlab/Simulink and its Power System Blockset (PSB). This model mathematically calculates cell output voltages and their consequent losses. It also calculates the ac output from the system by simulating an inverter dc input from the fuel stacks. The V-I curves and dynamics can be observed. The effects of variation in outputs for different inputs can also be observed. This model is easy to understand and it requires less computational time.Index Terms-Distributed generation, dynamic modeling and simulation, phosphoric acid fuel cell, power conditioning system. I. INTRODUCTIONRecently alternative or renewable energy is becoming more popular because of increasing energy consumption. People are also becoming aware of environment impact and declining fossil fuels. Common alternate energy sources are fuel cells, wind turbines, micro-turbines, photovoltaic etc. These are also referred as distributed generation (DG). Fuel cells have drawn more attraction from different distributed generation since it has the potential capability of providing both heat and power [1].A fuel cell (FC) is an electrochemical device that converts the chemical energy of the fuel directly into electrical energy. Fuel cells have a low environmental impact and operate silently in practical situations with high efficiency and long lifetime. So they can represent a very good option as a DG [2].A power conditioning stage is essential to produce commercial ac power since the output of a fuel cell is dc electricity [3]. So fuel cell plants can produce this ac power. Generally there are three major subsystems in a fuel cell plant which are a reactant supply subsystem to convert natural gas to a hydrogen-rich gaseous fuel, a power section subsystem including a thermal management assembly to generate dc power and a power conditioning subsystem to convert the dc power generated in the power section subsystem to ac power [4]. Fig. 1 shows the process.According to the type of electrolyte used, the most Among them, PAFC has one of the most advanced technologies available commercially. It is possible to improve the performance of a fuel cell by changing the operating variables (e.g. pressure, temperature, gas composition, current density etc.). It is important to select an operating point (cell voltage and related current density) of a fuel cell till the system requirements are satisfied [6].This paper represents a model of the last two subsystems of Fig. 1. A dynamic modeling of phosphoric acid fuel cell (PAFC) system including dc to ac power conversion is proposed here. The model is based on empirical equations. This model includes fuel stacks to produce dc power and a dc to ac inverter to produce ac power. The model is validated by Sim Power Systems (SPS) block set of Matlab...

This paper presents a closed-loop control of a 440kW fuel cell system including power electronics and grid side filters. Simulation results show the dynamics of a phosphoric acid fuel cell (PAFC) and its associated power electronics including grid connection. The proposed model is based on empirical equations and Simulink blocks. The modeling and simulation is done in Matlab/Simulink software with its Power System Blockset (PSB). This model mathematically calculates cell output voltages and their consequent losses. Moreover, this model includes dc power conversion of fuel cell output into ac and grid interface. Presented model is simple and easy to understand.