Flexible power control of fuel cells using sliding mode techniques

Abstract

The energy conversion system considered in this work consists of a fuel cell connected to a DC-bus through a switching converter. Particularly, the paper deals with the control of the electrical variables of this system. The control problem is addressed using tools of variable structure systems theory. The dynamic behavior of the system is first analyzed. Then, sliding mode algorithms to control electrical variables according to different power management objectives are developed. Thus, different control strategies such as fuel cell voltage/current regulation, maximum power point tracking and/or load current regulation can be followed. After studying their stability properties, these algorithms are combined to achieve a globally stable control over the whole electrical operating locus of the fuel cell. Experimental results on a test circuit are presented.