Dynamical behaviour and stability analysis in SEPIC converter based on sliding-mode control

Abstract

A hysteretic current-controlled SEPIC converter, which uses the sum of two inductor currents as the control variable, is discussed. The operation states of the converter are studied based on the theory of sliding-mode control. The equivalent control and relative differential equations on the sliding surface are derived, based on which, the stability of equilibrium point is analysed with the calculation of eigen-values. With numerical calculation and computer simulation, it is shown that the equilibrium point will lose the stability via a Hopf bifurcation when the reference current increases. The other circuit parameters will make influence on the first bifurcation point of reference current. Subsequently, the converter will exhibit complex dynamical behaviour, including limit cycle, double limit cycle, quasi-periodicity and chaos, by increasing the reference current furthermore.