Robust input–output sliding mode control of the buck converter

An input–output based feedback controller is proposed for the sliding mode control of a large class of switched systems. The method avoids state measurements, or the use of observers, and it extends the sliding mode control design methodology to input–output descriptions of the plant. The approach regards the average Generalized Proportional Integral (GPI) output feedback controller as a guide for defining the switched implementation of the average sliding mode features via a Sigma–Delta modulation strategy. The considerations are circumscribed to the class of differentially flat systems. Experimental results are presented for a trajectory tracking problem on a DC-to-DC switched power supply of the “buck” type with unknown loads subject to abrupt variations.