Control-oriented discrete-time large-signal model of phase-shift full-bridge DC–DC converter

Abstract

In this paper, a new approach toward large-signal discrete-time modeling of phase-shift full-bridge (PSFB) dc–dc converter for discontinuous conduction mode operation has been introduced. Instead of averaging the circuit elements or state variables, this approach makes use of the inherent characteristics of the dc–dc converter by developing piecewise differential equations of the switching network in different time intervals. Then, these differential equations are analytically solved with appropriate boundary conditions in order to develop the discrete-time nonlinear model of the PSFB dc–dc converter. The developed nonlinear model captures the complete dynamics of state variables within a switching cycle. Another major contribution of this research work is an accurate linear model of PSFB dc-dc converter, which has been acquired by employing small signal approximations and change of variables. The proposed model has been compared to the previously reported large-signal models of the PSFB dc–dc converter. Detailed theoretical results have been included, which show excellent agreement of the proposed model with the original switching network.