Abstract:
In this thesis, a Sliding Mode Control (SMC) strategy is investigated for Proton Exchange
Membrane Fuel Cell (PEMFC) system. The strategy contains two control loops. The first loop
tries to maintain the stoichiometric oxygen excess ratio whereas the second loop stabilizes the
output voltage of the system. The basic problem with the operation of fuel cell system is that it
does not produce steady output voltage whereas most of the electrical appliances require stable
one. There is a variation in the output voltage as the load varies and it drops with the passage of
time even if the fuel supply is kept steady. It may conclude that to get rid of variable and
degraded output voltage, there is an inevitable need of voltage stabilization. The output voltage
stabilization is carried out via three approaches e.g. Proportional, Integral and Derivative (PID)
control, first order SMC and Higher Order Sliding Mode (HOSM) control using super twisting
algorithm. The simulation experiments are performed on a nonlinear state space mathematical
model that is validated with experimental results available in public literature. The comparative
study of the approaches confirms that the HOSM control provides robust performances as well as
optimizes the fuel consumption. The proposed controller therefore can be a step forward to make
the fuel cell technology inexpensive with optimal robust performance.
