Discrete-Time Modeling

This chapter introduces the process of discrete-time modeling of dc-dc converters not only from a theoretical perspective but also from a practical standpoint. It lays the theoretical foundations of the discrete-time modeling technique. The chapter provides a number of modeling examples and discusses the most interesting features of the discrete-time dynamics, some of which cannot be predicted well using averaged modeling techniques. It deals with an important class of converters where the switching event does not alter their topology-a notable example being the Buck converter. The discrete-time modeling procedure is illustrated through several practical examples. The chapter also shows that the exact discrete-time modeling framework is equivalent the impulse-invariant discretization when applied to time-invariant topologies. The exact discrete-time model can be obtained via impulse-invariant discretization of the conventional averaged small-signal model, provided that the overall delay is included as an equivalent transport delay.