A PEM Fuel Cells Control Approach Based on Differential Flatness Theory
Résumé
The article presents an approach to nonlinear control
of fuel cells using differential flatness theory and Kalman
filtering. First, it is proven that the dynamic model of fuel
cells is a differentially flat one which means that all its
state variables and control inputs can be expressed as differential
functions of specific stare variables which are the
so-called flat outputs of the system. By exploiting the differential
flatness properties of the model its transformation to an
equivalent linear form (canonical Brunovsky form) becomes
possible. For the latter description of the system’s dynamics
the design of a state-feedback controller is achieved. This
control scheme should be also robust to model uncertainties
and external perturbations. To cope with this problem the
state-space description of the PEM fuel cells is extended by
considering as additional state variables the derivatives of
the aggregate disturbance input. Next, a Kalman filter-based
disturbance observer is applied to the linearized extended
model of the fuel cells. This estimation method enables to
identify the disturbance and model uncertainty terms that
affect the system and to introduce a complementary control
element that compensates for the perturbations’ effects.
The efficiency of the proposed control scheme is evaluated
through simulation experiments.