Stability Analysis of a Voltage Mode Controlled Two-Cells DC-DC Buck Converter

In this paper we analyze the dynamics and stability of a power electronic two cell DC-DC buck converter for high and medium voltage applications. The system is under voltage mode PWM control with dynamic controller for the output voltage loop. Numerical simulations from the exact circuit model shows that the system can undergo some nonlinear phenomena in the form of bifurcations. Different kinds of behaviors of the system are detected by varying some design parameters. These behaviors occur after losing stability of the nominal periodic behavior. In order to explain these phenomena, we derive a discrete time model in the form of a Poincare map which accurately describes the dynamical behavior of the system. The linearized small signal discrete time model is also obtained. Numerical simulations confirm the theoretical predictions