ABSTRACT:
Fuel cell stacks produce a dc output with a 2:1
variation in output voltage from no-load to full-load. The output voltage of
each fuel cell is about 0.4 V at full-load, and several of them are connected
in series to construct a stack. An example 100 V fuel cells tack consists of
250 cells in series and to produce 300 V at full load requires 750 cells
stacked in series. Since fuel cells actively convert the supplied fuel to
electricity, each cell requires proper distribution of fuel, humidification,
coupled with water/their mal management needs. With this added complexity,
stacking more cells in series decreases the reliability of the system. For example,
in the presence of bad or mal performing cell/cells in a stack, uneven heating
coupled with variations in cell voltages may occur.
Continuous operation under these conditions may not
be possible or the overall stack output power is severely limited. In this
paper, a modular fuel cell powered by a modular dc–dc converter is proposed.
The proposed concept electrically divides the fuel cell stack into various
sections, each powered by a dc–dc converter. The proposed modular fuel cell
powered by modular dc–dc converter eliminates many of these disadvantages,
resulting in a fault tolerant system. A design example is presented for a
150-W, three-section fuel cell stack and dc–dc converter topology. Experimental
results obtained on a 150-W, three-section proton exchange membrane (PEM) fuel
cell stack powered by a modular dc–dc converter are discussed
KEYWORDS:
1. DC–DC
converters
2. fuel
cells
3. Power
conditioning renewable power
SOFTWARE: MATLAB/SIMULINK
SCHEMATIC DIAGRAM:
Fig: 1
Proposed modular fuel cell and modular dc–dc converter concept
CONCLUSION:
In this paper, a modular fuel cell stack and dc–dc
converter concept has been presented. It has been shown that the standard fuel
cell stack can be reconfigured into several sections with smaller cell count,
each supplying an isolated power module in the dc–dc converter, resulting in a
high-performance system. The proposed system has been shown to be fault
tolerant and can continue to operate at a reduced power level under fuel cell
or power module faults. Experimental results on a 12-V/150-W system demonstrate
that under normal operation, the proposed system is capable of producing 10%
additional power when compared to the traditional approach. In addition,
experimental results also confirm the operation of the system under stack failure.
REFERENCES:
[1]
L. Palma and P. Enjeti, “A modular fuel cell, modular DC–DC converter concept,”
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