Nonlinear sliding mode observer and control of high order DC-DC converters

In this paper, the application of the Sliding Mode Theory, in terms of observer and control design, to the DC-DC Single-Ended Primary Inductor Converter (SEPIC) is investigated. The choice and influence of the sliding surface regarding the state vector is presented. Usual sliding surfaces chosen to control other high order DC-DC converters are found not to work on the SEPIC. Thus, other surfaces are proposed here and which require the presence of more than one state variable. Also, an extended sliding mode observer is proposed to estimate the state vector. Results are experimentally validated.