PWM switch model of a buck-boost converter operated under discontinuous conduction mode

A computer analysis of PWM dc-dc converters operated in discontinuous conduction mode DCM is presented. The analysis is based on a linearized small-signal model of the converter ideal switching-cell (ISC), which is used as a sub-circuit inside the circuit simulation program. The sub-circuit is used in computer simulation of a PWM buck-boost converter, which is based on equivalent cir- cuits. A computer program for PWM dc-dc converters analysis, generates the symbolic expressions of the root locus and Bode plots of the control-to-output voltage transfer function, the input-to-output voltage transfer function, the input impedance, and the output impedance which are given both in symbolic and numerical expres- sion.