Dynamics and Stability Issues of a Discretized Sliding-Mode Controlled DC-DC Buck Converter Governed by Fixed-Event-Time Switching

This paper finds and investigates the application of fixed-event-time based discretized sliding mode (DSM) controller in dc-dc buck converter, to achieve fast transient response and high robustness under wide parameters variation. We show that how these can be achieved by integrating the concept of Utkin´s equivalent control law and discontinuous border-collision bifurcation (DBCB) theory developed for 2-D discontinuous piecewise smooth (PWS) maps. Moreover, based on derived 2-D discontinuous maps of DSM-controlled converter, we investigate its inherent steady-state dynamical properties or bifurcation behaviors under different parameters variation. Numerically as well as experimentally obtained bifurcation diagrams are then presented to show the domains of existence of different oscillatory modes and their sequence of occurrence. Such phenomena are not only useful to study the robustness of the system but may also facilitates to design the input filter with fast transient response. The performance of DSM controller is experimentally verified and compared with hysteresis and classical peak current-mode controller.