Stability analysis and bifurcations of SEPIC DC-DC converter using a discrete-time model

In this work, stability analysis and bifurcations of a SEPIC dc-dc converter, operating in the continuous conduction mode (CCM) and under current-programmed control is carried out by means of a discrete-time model. Large-signal model is built, and its corresponding linearised version is performed in order to study the stability of the nominal (1-periodic orbit) operating regime. Varying the reference current, it is obtained that the system functioning changes from a stable buck-like converter to an unstable boost-like converter. The 1-periodic orbit loses its stability via flip bifurcation (FB) and the resulting attractor is a 2-periodic orbit. This latter, bifurcates to chaos via border collision bilification (BCB). It will be shown that allows in order to get a boost-like converter with a stable periodic behavior, the control polarity should be inverted.