Optimal design of Ćuk step-up converter for photovoltaic energy systems

Ćuk step-up converters can be used as power conditioners in PV systems. However it is intricate to design the converter circuit which offers satisfactory performance in both transient and steady states. This paper presents a model-based optimal design scheme for the Ćuk step-up converter. A small-signal transfer function model for this converter is presented. This describes output voltage variations in response to the perturbations of either input voltage or switching duty ratio and the model exhibits non-minimum phase features. Using this model an optimal circuit design scheme is derived using the criteria of required ripple percentage at steady state and minimized time integral of squared transient response error. A Ćuk step-up converter thus designed is applied to control a PV panel for the maximum power point tracking. The result of such a system is presented.