Ćuk Step-Down Converter Design for Optimum Transient Performance and Minimum Ripple

A Ćuk step-down converter has operating modes of variable input, constant output voltage suitable for controlling a solar photovoltaic (PV) power generation system, and variable output–constant input voltage applicable to a variable speed motor drive. For these applications a novel circuit design procedure has been developed which achieves the criteria of suppressing ripple in the input current and output voltage at steady state, and minimizing the time integral of squared transient response errors. New results are shown for the transient responses of a converter working with a nonlinear power source such as a photovoltaic generator. The designed converter has been tested in simulation, and validated experimentally by controlling a practical photovoltaic panel.