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Design and Development Assessment a Power Converter to Spply Stand-Alone Loads from a 1KW Polymer Electrolyte Membrane Fuel Cell

Shahmohammadi, Ahmad | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46731 (46)
  4. University: Sharif University of Technology
  5. Department: Energy Engineering
  6. Advisor(s): Rajabi, Abbas; Tahami, Farzad; Roshandel, Ramin
  7. Abstract:
  8. Isolated electric energy systems are often needed to supply 3 kind of electric loads. This could be caused due to geographic isolation, the necessity of load mobility, demanded values of voltage and current that are not compatible with the local networks. This makes the design and construction of stand-alone energy systems a must. Because of sustainability concerns and enviromental pollution avoidance, Modern designs are being pushed towards cleaner energies and technologies. Polymer electrolyte membrane type fuel cells are among the new technologies that are being considered as a good alternative to the traditional power sources used for stand-alone energy systems. Although the basic principles of operation of the fuel cells are known since 1839, this is a technology that is far from being mature. A dynamic model of fuel cell has been exerted on the system, but control of the lectrochemical variables is not deal with. Here, the dynamic model is realy a black-box dc power supply with certain current/voltage characteristics and dynamics. The energy provided by the fuel cells needs to be conditioned to the levels and characteristics required by the loads to be fed. The problems when working with fuel cells can be split in two big groups of interest, the first, being the handling and control of the electrochemical variables, and the second, the handling and control of the electrical variables taking care of the limits imposed by the dynamics of the fuel cell unit. This work deals with the second group of concerns. This converter has 3 units :
    • Step up unit (STU)
    • Inverter unit
    • Auxiliary power unit (APU)
    The STU, boosts the fuel cell voltage up to 400 volts and delivers it to DC bus. Next, This DC voltage is converted to AC voltage through the inverter simultaneously, unwanted harmonics has been compensated. The APU is included by battery set, charger and decharger circuits and, as the name implyes so, it helps to improve fuel cell dynamics and supplying overload for a certain period of time. While the converter is working under sub-nominal load, the excess power is charged in to the battery set. This work presents analysis, design, control and development assesment of the electric energy conditioning system for a polymer electrolyte membrane type fuel cell to act as a stand-alone dc-ac inverter to feed linear or nonlinear loads with big variations.At the end, suitable control strategy for the converter, Printed Board Circuit (PCB) docucment and the project’s Bill Of Material (BOM) has been represented. Also, the measuring and power switch’s driver PCB has been constructed and in open-loop type control, the STU has been tested under nominal loads
  9. Keywords:
  10. Proton Exchange Membrane (PEM)Fuel Cell ; Control Strategy ; Dynamics Models ; Power Converters ; Stand-Alone State ; Frequency Control ; Voltage Control ; Printed Circuit Board ; Voltage and Current Harmonic Content ; Electrical Variables Control

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