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.