Bifurcation in a dual channel resonant DC-DC converter

The paper reports first time subharmonic, quasiperiodic and chaotic operation in one member of a double channel resonant DC-DC power converter family. The converters of this family can operate both in symmetrical and in asymmetrical mode. The study presented in the paper is restricted to the buck configuration in symmetrical operation. A brief summary of the configuration and basic operation of the converter is followed by the study of some nonlinear phenomena of the output voltage control loop of the resonant buck converter. The nonlinearity is caused by the dependence of the turn-on time of the controlled switches on a system state variable. The rather strange behavior exhibited by the feedback controlled converter is studied by simulation. Two kinds of route lead to the chaotic operation: a period doubling scenario and a quasiperiodic one, caused by a Hopf bifurcation. The paper presents a number of simulations results of this behavior in form of time functions, bifurcation diagrams, Poincare´ maps and state-space trajectories