Dynamic analysis and control of dc/dc boost converters used in stand-alone PV systems

A stand-alone photovoltaic (PV) system connected to a resistance load through a dc/dc boost converter is considered. Taking into account the PV source voltage-current nonlinear dependence as well as the dc/dc boost nonlinear dynamic model, an extensive system analysis is conducted. It is proven that as the load power becomes smaller than the maximum power input provided by the PV source, the system acquires the minimum phase property with respect to the output voltage, while the domain of attraction of the stable zero dynamics of the system becomes larger. Exploiting this property, a simple adaptive-based direct output voltage controller is implemented, which acts independently from the system parameters and the equilibrium guaranteeing stability and convergence to the desired operating point. Extensive simulations results verify the theoretical analysis and the system good performance.