Averaged modelling of switched-inductor cells considering conduction losses in discontinuous mode

Many PWM DC-DC converters contain a switched-inductor cell for which an average-value model is required. However, the presence of parasitics associated with the cell´s components complicates the development of accurate averaged models, especially for the discontinuous conduction mode. Here is described an improved full-order, large-signal averaged switching cell. The proposed averaged cell takes into account conduction losses as required by the energy conservation principle and provides a more accurate duty-ratio constraint. The final model shows improvement over several previously established averaged cells in predicting large-signal, time-domain transients as well as small-signal, frequency-domain characteristics