Adaptive second order sliding mode control of PEM fuel cell air feed system

In this paper, we have presented a novel cascade scheme to control the moto-compressor of a Polymer Electrolyte Membrane Fuel Cell (PEMFC). The control objective is to operate the PEMFC at its optimal power output, which is achieved by maintaining the oxygen excess ratio between 2 and 2.4. The proposed control strategy is based on two cascaded adaptive second order sliding mode controllers which regulate the compressor speed in response to oxygen excess ratio error (Fig.1). The compressor speed is determined from its position using an adaptive super twisting differentiator. The use of adaptive controllers provides better results than fixed parameter super twisting control, as it has less chattering, and better transient performance under load variations and parametric uncertainties. These results have been obtained from simulation, and have been presented in the paper. The effectiveness of this controller is evident in the results.