Design guidelines and control of DC-DC cascaded buck converters

This paper deals with the voltage control of DC-DC cascaded buck converters. A steady-state analysis is presented, providing the design guidelines for all the parameters of two cascaded buck converters based on analytical expressions. In the sequence, a state feedback model of the converter is obtained, and after linearized. A small-signal model in the state space is provided and then augmented with an extra state variable representing integral action. A state feedback controller is used, and its gains are computed with the help of a linear quadratic regulator (LQR). The impact of parametric variations over the dynamic response are investigated and simulation results of the closed-loop system are presented, confirming good transient and steady state performances of the converter under load variations.