Research And Simulation Of Fuel Cell Power System

Since environmental pollution, energy crisis and other global problems have become increasingly prominent, the discussion of reducing emissions and developing new energy technology has become the most important technological development issue in the 21st century. Because of the advantage of high energy conversion efficiency, zero emission and low noise, fuel cell is the first-choice device among different kinds of power generations and power equipments.Fuel cell is an electrochemical power generation device, which converts the chemical energy stored in the fuel and oxide into the electrical energy based on the electrochemical principle. Because there is no Carnot cycle during the reaction of fuel cell and hydrogen supplied as the fuel is one of the clean energy source, it has been wildly used in the area of aerospace, electric vehicles, ships, submarines, small mobile power, and distributed power plants, etc.The project-fuel cell UPS for communication device is collaborated by Clean Energy Center, Temasek Polytechnic, Singapore and SingTel Company, which provided a large amount of funding to achieve this research. The 5kW fuel cell distributed generation system is researched and designed. The simulation model has been built in the environment of MATLAB/SIMULINK, which demonstrated that output AC is steady enough to response the load's demand.There are some drawbacks in the fuel cell, such as long starting time and slow dynamic response. Ultra Capacitor is introduced in the system for the energy buffer module, which can not only store and provide energy rapidly but also control and optimize the energy flow to make the system reliable and steady. Because of ultra capacitor, the output of fuel cell is steady and vibrant current is reduced in the proton exchange membrane. Fuel cell, ultra capacitor, DC/DC converter and DC/AC inverter dynamic model have been built by using MATLAB/SIMULINK software, and the simulation output of the system demonstrated that it is reliable theoretically.In order to control the molar flow of the inlet gas, charge and discharge current of ultra capacitor and the voltage of the DC/AC inverter, there are different kinds of control methods have been adopted. FLC (Fuzzy Logic Controller) has been introduced to control the fuel cell's molar flow of hydrogen, which enhanced the performance of fuel cell's output and reduced the dynamic response time. As for ultra capacitor, PI controller and Fuzzy Logic controller are used to control ultra capacitor module. PI controller is mainly applied in the DC/DC converter and DC/AC inverter to adjust the duty through the PWM method and FLC is mainly used to decide the reference current of ultra capacitor.To verify the practicability of the whole system, fuel cell control, super capacitor control, data display and energy control management modules have been designed from the perspective of system design, in this paper. According to each functional module designed in the paper, fuel cell UPS for communication device's hardware has been completed. After testing, the stable DC output voltage and adjustable power can meet the requirement of the load of the communication device.