Reduced-order discrete modeling method and nonlinear analysis of a discontinuous conduction mode buck converter with a constant power load

Abstract

Discontinuous conduction mode (DCM) DC–DC converters with constant power loads (CPLs) are the widely used power electronics cascade topologies of distributed renewable energy power systems. There exists rich nonlinear dynamics of these cascade topologies, which tend to induce unstable operation of the distributed renewable energy systems. However, the difficulties of output regulation and discrete modeling for DCM DC–DC converters with CPLs decelerate the progress of the study of nonlinear dynamics in these systems. To study the mechanism of these nonlinear dynamics for DCM DC–DC converters with CPLs, this paper proposes a reduced-order discrete modeling method for the system by considering a current-controlled discontinuous conduction mode (CC-DCM) Buck converter with a CPL as example. The nonlinear dynamics of CC-DCM Buck converter with a CPL are studied by using the proposed reduced-order discrete model. The theoretical results display complex nonlinear behaviors of this system, such as multicycle orbits, states jumping between different periodic orbits or between periodic orbits and chaos, chaotic states, and orbits interleaving with the variation of the power of CPL. Both simulation and experimental results illustrate the effectiveness of the proposed reduced-order discrete modeling method and the correctness of nonlinear characteristic analysis of the system. Based on the proposed reduced-order discrete modeling method, the problems of discrete modeling DCM DC–DC converters with CPLs in DCM states using the stroboscopic mapping method are resolved. This study is expected to provide reference for the further study and application of these power electronic cascaded systems.