Low-frequency sampled-data models of switched mode DC-DC converters

Practical implementation of a low-cost digital controller for switched-mode convertors is feasible if the sampling rate is lower than the switching frequency. The authors present a sampled-data model of a switched-mode converter applicable for the low-frequency range. The assumption made is that the sampling rate is sufficiently high as dictated by the sampling theorem. It is shown that the models are linear for small-signal operation but represent a bilinear system under large-signal conditions. The models could be useful for the design of a microprocessor-based controller for switched-mode convertors, with improved transient response. Two examples of possible applications of the model are discussed: as a fast and efficient time-domain simulator and as a tool for the analysis and design of a fast-turn-on boost converter