Singular Perturbation Stability Analysis of Three Phase Two-Level Power Converters

In this paper, the stability of a three phase two-level rectifier is studied. This type of power converter has two operation modes, as rectifier or as inverter. The dynamics of the rectifier consist of a set of equations highly nonlinear. Through the definitions of the instantaneous active and reactive powers, the model of the system is sometimes expressed in terms of power instead of current. Since this new model takes the form of a standard singular perturbation model, the system can be studied in separate time scales. This work propose an analysis of the system in two-time-scale based on the decomposition of the model into reduced (slow) and boundary-layer (fast) models where both should satisfy some conditions to prove the stability of the equilibrium point of the whole system. This analysis will show the stability of the equilibrium of the system via Lyapunov's method and, consequently, will eliminate stiffness difficulties for the implementation of a future controller.