Fast computer-aided simulation of switching power regulators based on progressive analysis of the switches' state

A new method for time-domain analysis of power electronics circuits is developed based on the following principles: (a) at each instant, the switching topology is a linear time-invariant circuit; (b) at each instant, the voltage across a capacitor and the current through an inductor have a certain value, like an independent voltage- or current source, respectively; (c) generally, no switching relationship between the externally and internally controlled switches may be assumed; (d) prior knowledge of the internally controlled switches' operation is not available; and (e) the switching action may change the response of the circuit immediately after the switching moment, implying that some constraints may be in violation of the presumed switches' states. The algorithm is based on solving a system of algebraical modified nodal equations at each integration step. The number of systems to be solved equals the number of topologies the converter goes through in a cycle. This feature, and the fact that no solutions of time-differential equations or Laplace transform inverses are required, cause the algorithm to be a fast one. At each step, the presumed state of all the switches is checked, and if some constraints are violated, the program looks for another valid topology. An example, with parasitic effects taken into account, is presented; the experimental results, as well as the simulation results obtained by using other available algorithms, confirmed the accuracy of the results achieved with the presented approach