Modeling and Control of a Cascaded Boost Converter with a Single Switch

In this paper, a controller design methodology is given for a cascaded boost converter with a single switch using current-mode control. Nonlinear and linear models are presented, the later exhibits fourth-order characteristic dynamics with right-half side zeros. The proposed control scheme is based on sensing the current of the switch and using it for feedback purposes. When the current loop is introduced, the fourth-order dynamics of the converter is changed to a dominant first-order, which simplifies substantially the controller design of the outer loop. For this loop, a conventional controller is designed. The design-oriented analytic results allow the designer to easily pinpoint the control circuit parameters that optimize the converter's performance. At the end, experimental results are given for a 23 W current-mode regulator.