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

A sampled data model of a switched mode converter applicable for the low-frequency range is presented. 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 discrete system under large signal conditions. The models could be useful for the design of microprocessor-based controllers for switched mode converters, 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. Experimental measurement and computer simulation of the responses to large steps of the duty ratio in a boost converter demonstrate the accuracy of the model at the tested low-frequency region. The bilinear model can be used as a simulation tool for fast and efficient computer-aided analysis and design. The main limitation of the model is its restriction to the low-frequency range.<
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