| Summary: | Thesis submitted in partial fulfilment of the requirements for the degree
Magister Technologiae: Electrical Engineering
in the Faculty of Engineering
at the Cape Peninsula University of Technology
2008 === Fuel cell technology is an emerging technology that provides a highly efficient, quiet
operation, reliable, and environmentally friendly energy conversion system for stationary,
automobile (vehicle), and portable applications. An electrochemical process combines
hydrogen fuel and oxygen from air to produce water, and in the process it produces
electricity and heat. Fuel cell stationary applications which include residential, office
buildings, hospitals, hotels, airports and others have received greater attention for their
ability to utilize the heat generated for space and water heating. This combined heat and
power (CHP) process increases the energy conversion efficiency greatly which in turn
save cost of energy usage.
Different power converter topologies for fuel cell systems residential applications are
presented in this thesis for efficiency, cost, component count, input ripple current
minimization technique, reliability for comparison analysis. The commercial feasibility of
fuel cells rests on the cost of the fuel cell system and operating efficiency and fuel cost.
The proposed power converter topology consists of two front end DC-DC converters.
The first front-end DC-Dc converter is tightly controlled while the second is a full bridge
four interleaved DC-DC converters. Advantages of the proposed topology are reduced
input ripple current, high efficiency, low maintenance cost, smaller size, modularity,
redundancy. Design overview as well as simulation results are presented.
Fuel cell simulation test results, including transient response are displayed and
analyzed. The concept of interleaving of multiple units of the De-De converter is
proposed. Interleaving enables paralleling multiple units of the converters to achieve a
high combined power. This results in using semiconductor power devices of lower
current rating, lowering sizes of input and output capacitors and reducing the output
ripples. Simulations results are presented that verify the concept of interleaving.
Preliminary work to implement interleaving is presented, and future work is
recommended.
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