Boundaries between fast- and slow-scale bifurcations in parallel-connected buck converters

Abstract

This paper studies a system of parallel-connected dc/dc converters under master-slave current sharing and proportional-integral (PI) PWM control. Two distinct types of bifurcations can be identified. Depending on the value of the integral time constant, the system exhibits either a slow-scale bifurcation (Neimark-Sacker bifurcation) or a fast-scale bifurcation (period-doubling). Extensive simulations are used to capture the behaviour. Trajectories before and after these bifurcations are shown. The boundaries between these two types of bifurcations are located. Parameter spaces of the feedback controller for stable and unstable operation are presented.