State and disturbance observer-based predictive control for DC–DC converters integrated with a photovoltaic system

This paper is concerned with discrete-time integral sliding mode observer (DISMO)-based predictive control to regulate the photovoltaic integrated DC–DC Buck Converter (PVBC) output voltage. First, we considered the variations in the generated voltage of the PV panel from its equilibrium point due to environmental conditions as disturbances and formulated the state-space representation of PVBC. Based on this model, we proposed DISMO, which involves the development of a novel injection term in its structure to estimate the inductor current and the voltage of the photovoltaic (PV) panel. Further conditions for the existence of such an observer are given. Second, we developed the DISMO-based predictive control using precise predictions of the output voltage by incorporating these estimates from DISMO to achieve the regulated output voltage of PVBC. Finally, we demonstrated the procedure for designing DISMO and performed simulations to validate and compare the results of the proposed DISMO-based predictive controller with that of the proportional-integral-based controller.