A general linear continuous model for design of power conditioning units at fixed and free running frequency

A linear continuous low frequency small signal model, valid for all types of converters (boost,buck, buck boost), both in heavy and light modes, is presented in this paper. Its interesting characteristics are that it is valid for free running as well as for fixed frequency converters and that it allows easily to take into account both input and output filters. Thanks to its modularity and its simple general form, it gives a strong insight into the influence of various parameters. (such as input filters) on performance dynamics and into the design of efficient control loops. Finally, a computer program, using state analysis, has been developed allowing the automatic performance analysis of complete controlled converters.