An Hybrid Fixed Frequency Controller Suitable for Fuel Cells Applications

The authors investigate a hybrid constant switching frequency current controller that uses both turn-on and turn-off current and sliding mode control techniques. It is suitable for one-, two- or four-quadrant operations and can be used with most topologies of DC-DC converters. Two methods are presented to study characteristics of the proposed current controller. First, a high frequency average model is presented. It allows to get some basics design concerns such as overflow and time response. Second, to explain some behaviors not predicted by the high frequency average model, a mathematical analysis derived from chaos theory is developed