Complex Phenomena in SEPIC Converter Based on Sliding Mode Control

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 eigenvalues. With numerical calculation and computer simulation, it is shown that the equilibrium point will lose the stability via a Hopf bifurcation when the current reference increases. Subsequently the converter will exhibit complex dynamical behavior including limit cycle, double limit cycle, quasi-periodicity, and chaos by increasing the current reference furthermore.