Design of controller for buck-boost converter

The problem of output regulation with guaranteed transient performances for buck-boost converter with inverting topology is discussed. The fast dynamical controller with the relative highest derivative of output signal in feedback loop is used. Consequently, two-time-scale motions are induced in the closed-loop system. Stability conditions imposed on the fast and slow modes and sufficiently large mode separation rate can ensure that the full-order closed-loop system achieves the desired properties in such a way that the output transient performances are desired and insensitive to external disturbances and parameter variations in the system. The existence of stable limit cycle in the fast motion subsystem gives the robustness of the output transient performances in the presence of external disturbance and parameter uncertainty. The describing function method is used to analyze the existence and parameters of stable limit cycle.