Nonlinear Dynamics and Stability Analysis of a SEPIC Converter for Stand-Alone PV Systems

This paper presents a study of the nonlinear dynamics and stability analysis of a DC-DC (Single-Ended Primary Inductance Converter) (SEPIC) fed by a nonlinear photovoltaic (PV) generator in battery charging mode operation. The SEPIC converter employs a fixed frequency pulse width modulation (PWM). The control objectives are twofold. In one hand, the controller forces the PV generator to work at its maximum power point. On the other hand, the input variables of the converter are controlled in such a way that its input port behaves like a loss free resistor (LFR) in the average sense. A detailed and accurate modeling of the system in continuous and discrete-time is first addressed and an analysis its nonlinear dynamics and bifurcation behavior is presented. Simulation results using detailed switched model show that the system can exhibit period doubling bifurcation when appropriate system parameters are varied. The stability analysis of the system periodic orbits is performed by calculating the eigenvalues of the monodromy matrix obtained from Floquet theory and Filippov method.