Theoretical and experimental investigation of bidirectional Hopf bifurcations in cascade DC-DC buck converters

This paper deals with two types of bidirectional Hopf bifurcation phenomena in two-stage cascade DC-DC buck converter, which is a popular design solution for obtaining larger conversion rates in distributed power systems (DPS). By means of "exact" cycle-by-cycle numerical simulations, it is found that two types of bidirectional Hopf bifurcations that never occur in standalone buck converter are observed under the variations of some particular circuit parameters. Based on the derived averaged model, theoretical analysis is performed to identify the two types of bidirectional bifurcations by judging in what way the eigenvalue loci of the Jacobian move, and further to reveal their underlying mechanisms. In addition, some behavior boundaries are given in parameter space, and some rules are proposed to avoid the occurrence of the bidirectional Hopf bifurcations. Finally, experimental results are presented for verification purposes.