Automatic modeling of PWM DC-DC converters

Different small-signal models are available for describing the dynamics of pulse width modulators (PWM) dc-to-dc converters. Discrete time models reach the best compliance in real life situations. Some converter control modes, in particular phase shifting, provide advantages of modeling in discrete time. On the other hand, the burden of getting such exact models is often tedious. Currently, automatic tools are available that are able to provide the state-space model in discrete time of any PWM dc-dc converter switching at constant frequency. The authors claim that the use of these tools is advisable for the analysis and control optimization of switching power supplies. To support their opinion, this letter refers to a new, very accurate small-signal model of a phase-shifting converter which has been published recently. Its excellent performance, as well as the difficulties of the derivation procedure, are compared with the precise forecasts and the short processing time of an automatic modeling tool. The paper concludes in favor of automatic modeling.