Analysis and Design of an Adaptive Multiloop Controlled Two-Winding Buck/Boost Regulator

Small-signal low-frequency linear average model is derived for a multiloop controlled two-winding buck/boost converter employing average techniques and the describing function method. The model reveals that a well-designed multiloop control can provide a second-order zero adaptive to output filter parameter changes due to component tolerances, temperature changes, aging, and the effect of duty cycle modulation. It also can provide stabilization effect by shifting the positive zero to the left-half S-plane. Design guidelines are formulated to optimize regulator-loop dependent characteristics.