Modeling and analysis of the DC/DC fourth-order PWM converters

This paper aims to show how the Matlab environment can be used for both modeling and analysis of DC/DC fourth-order PWM converters with both continuous and discontinuous conduction mode (CCM and DCM), coupled or separate inductors and parasitics included. Based on the SSA method easily modified, the program performs the averaged steady state model and the canonical dynamic (AC small signal) model with averaged characteristic coefficients. Thus, all the three forms of the dynamic model of converter are obtained: the mathematical model, the model with equivalent circuit and the functional block diagram. Also, it computes the boundary between DCM and CCM, the decay interval, the efficiency, the static and dynamic properties of the converter. The external characteristics, the frequency responses and any function of the converter are computed and plotted too. This program performs the modeling and the analysis of four configurations: nonisolated Cuk, Sepic and Zeta PWM converters and the ripple-free input-current PWM boost converter. Some analysis results of the Cuk PWM converter with DCM, parasitic included and coupled inductors are given in order to illustrate the utility of this program. These results have been in a close agreement with the experimental data.