Performance optimization of Cuk converters by sliding-mode control

A novel approach to the design of sliding mode controllers for Cuk power converters is presented, which is valid for both complete status feedback (fourth-order controller) and reduced status feedback (second-order controller). According to the proposed design criteria, both control techniques ensure excellent static and dynamic performances, also resulting in simple control implementation and minimum size of the energy transfer capacitor. Experimental results are reported, and compared with those obtained with other popular control techniques. The proposed approach has three main advantages: control implementation is very simple; large-signal stability, nonoscillatory response of all state variables, and short settling time are ensured in any operating condition; and the transfer capacitor can become very small, since decoupling of input and output stages is not required