As the world seeks to find alternative means to produce clean power, fuel cells emerge as a promising source of power generation. Depending on their type, fuel cells can be utilized for a wide range of applications, varying from few Watts to mega-Watt applications. They have been recognized as promising candidates for power generating devices in the automotive, distributed power generation and portable electronic applications. Fuel cells need to be coupled to additional Balance of Plant (BOP) components to form Combined Heat and Power (CHP) units. These units can be utilized in remote areas where connection to a power grid is not feasible. Therefore, fuel cells have the potential to provide reliable distributed power generation as discussed in Proton Exchange Membrane (PEM) fuel cells have been the subject of a great deal of interest over the past decades, since their development for use by NASA on their first manned space vehicle. In addition, their use in the transportation sector is considered to be efficient, clean and produce zero emission of green house gases. In this type of fuel cells, hydrogen fuel and oxygen, or the oxygen in air, are used to generate electricity as well as water and heat.
To facilitate the design and experimentation processes for fuel cells, computer models are commonly used as valuable tools. By simulating the system's transients, the designer may perform the necessary analyses to investigate fuel cell performance while eliminating the need for implementing a physical prototype of the system. This can significantly accelerate the experimentation process. In addition to the
PEM fuel cell design, other significant components of the overall power system include the conditioning circuits and their associated controllers. Those circuits that attempt to condition the unregulated voltage output of the fuel cell stack are a DC-DC converter and a DC-AC inverter. The converter circuit is used to increase the DC voltage of the fuel cell to an appropriate DC value that may be used for various applications. On the other hand, an inverter, which may act as the interface between the fuel cell stack and the power grid, is used to convert the regulated DC output of the converter into an AC signal. The control of the DC-DC converter and DC-AC inverter can be accomplished using various control methodologies.
The application of fuzzy logic has been evaluated in literature for the control of power electronics circuits such as the DC-DC converter. The resulting algorithm based on fuzzy logic is found computationally efficient compared algorithms based on linear control laws. Simulation studies have shown the superiority of Fuzzy Logic Controller (FLC) over conventional control methods. The use of fuzzy logic in fuel cells applications has also received considerable attention in literature. Experimental results show that the efficiency with which a fuel cell generates electricity when controlled by a fuzzy controller is 37%, which exceeds the 14.67% efficiency when applying the typically used PID controller. This paper presents a MATLAB/Simulink computer model that simulates the behaviour of a PEM fuel cell as well as the mentioned conditioning circuits. In addition, the paper presents the design and simulation of fuzzy logic control and Pulse Width Modulation (PWM) techniques that aim to control the DC-DC converter and DC-AC inverter circuits, respectively. The model presented demonstrates the use of the FLC in conjunction with the PEMFC Simulink model and that it is the basis for more in-depth analytical models.