Switchings, Bifurcations and Chaos in DC/DC converters

Nonlinear phenomena in closed-loop pulsewidth modulated (PWM) dc/dc converters are analyzed. We introduce a new discrete time nonlinear map—the A-switching map—which is related to the asynchronous switchings, i.e., the changes of converter configuration occurring within the modulating period. This map is compared with the stroboscopic map, which is typically used in the study of dc/dc converters. Analytical conditions for the occurrence of periodic orbits and flip bifurcations are obtained. Moreover, necessary conditions for infinite local stretching on the phase space are derived. Finally, a possible explanation of the sudden jump to chaos exhibited by dc/dc converters is proposed. Analytical and numerical results can be applied to all fundamental dc/dc converter topologies. The case of the voltage-controlled buck converter is treated in detail.