SCOS: a state space, time-varying topology simulator for the analysis of controlled switching converters

A simulator for controlled switching circuits, based on the approach of a time-varying topology, is presented. State-space equations of the circuit are formulated, and updated at each switch commutation, through a suitable linear transformation. An ideal model is used for switches, avoiding the numerical stiffness due to the insertion of fictitious impedances in the circuit. The feedback control system is modelled in terms of poles and zeros and by using user-defined functions to describe the control law of the switches. The simulator is suitable for application on a personal computer since a minimum-size equations set has to be resolved and good numerical stability is exhibited. Simulations of a regulated buck power converter, including soft-start and overcurrent protection, and of a novel high quality AC-DC PWM power converter are reported