Small-signal modeling of the tapped-inductor converter under variable frequency control

In this paper, a small-signal averaged model for the tapped-inductor (TI) converter under variable frequency control, which operates at the critical conduction mode (CRM) (the boundary between continuous conduction mode (CCM) and discontinuous conduction mode (DCM)) is presented. Based on the state-space averaging approach the state variable derivatives and the constraints that account for variable frequency control lead to full-order small-signal model. And the special behavior of the inductor current in the CRM reduces the order of the basic state-space averaged model by one. The full-order model and reduced-order model predictions are verified with experiment measurements on a prototype TI buck converter.